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1
ComputerComputer
Architecture Architecture andand
MicroprocessorMicroprocessor
22
Computer Architecture
& Microprocessor
Session ISession I
Number SystemNumber System ConversionsConversions Binary OperationsBinary Operations CodeCode Logic GatesLogic Gates Boolean AlgebraBoolean Algebra Registers & CountersRegisters & Counters Computer LanguagesComputer Languages
33
Computer Architecture
& Microprocessor
Number SystemNumber System
Systematic representation of data in Numerical FormatSystematic representation of data in Numerical Format
Decimal Number SystemDecimal Number System 0 to 9 0 to 9
Binary Number System Binary Number System 0 and 1 0 and 1
Octal Number SystemOctal Number System 0 to 7 0 to 7
Hexa Decimal Number SystemHexa Decimal Number System 0 to 9 and A to F 0 to 9 and A to F
44
Computer Architecture
& Microprocessor
Decimal Number SystemDecimal Number System
Uses digits from 0 to 9.Uses digits from 0 to 9.
Has a base of 10Has a base of 10
Value of digit corresponds to its position in the numberValue of digit corresponds to its position in the number
number X (base)number X (base)position-1position-1
Example :Example :
4954951010 , 84 , 841010
55
Computer Architecture
& Microprocessor
Binary Number SystemBinary Number System
Computer uses the Binary Number System Computer uses the Binary Number System
Consists of numbers 0 and 1Consists of numbers 0 and 1
Bit (Bit (BBinary diginary digitit))
Byte (8 - bits)Byte (8 - bits)
Example:Example:101010102 2 , 1110, 111022
66
Computer Architecture
& Microprocessor
Octal Number SystemOctal Number System
Uses the digits from 0 to 7.Uses the digits from 0 to 7.
Has a base of 8Has a base of 8
can be represented by a group of 3 bitscan be represented by a group of 3 bits
Example:Example:
1231238 8 , 435, 43588
77
Computer Architecture
& Microprocessor
Hexa Decimal Number SystemHexa Decimal Number System
Uses the digits from 0 to 15.Uses the digits from 0 to 15.
Numbers from 10 to 15 represented by alphabets A through FNumbers from 10 to 15 represented by alphabets A through F
Has a base of 16Has a base of 16
Can be represented by a group of 4 bits. Can be represented by a group of 4 bits.
Example:Example:
B3A1B3A116 16 , 98C, 98C1616
88
Computer Architecture
& MicroprocessorNumber System TableNumber System Table
Decimal Decimal Number Number SystemSystem
Binary Binary Number Number SystemSystem
Octal Number Octal Number SystemSystem
Hexa Decimal Hexa Decimal Number Number SystemSystem
00
11
22
33
44
55
66
77
88
99
1010
1111
1212
1313
1414
1515
00000000
00010001
00100010
00110011
01000100
01010101
01100110
01110111
10001000
10011001
10101010
10111011
11001100
11011101
11101110
11111111
00
11
22
33
44
55
66
77
1010
1111
1212
1313
1414
1515
1616
1717
00
11
22
33
44
55
66
77
88
99
AA
BB
CC
DD
EE
FF
99
Computer Architecture
& Microprocessor
Conversion of decimal Number to Hexadecimal NumberConversion of decimal Number to Hexadecimal Number
To convert, divide the decimal number by 16 successively To convert, divide the decimal number by 16 successively
ExampleExample
To convert 540 to decimalTo convert 540 to decimal
16 54016 540 16 33 -1216 33 -12 2 - 1 2 - 1
The decimal equivalent of 540The decimal equivalent of 54010 10 = 21C= 21C1616
1010
Computer Architecture
& Microprocessor
Conversion from Hexadecimal to DecimalConversion from Hexadecimal to Decimal
Multiply the digits of the number by the powers of 16 and addMultiply the digits of the number by the powers of 16 and add
ExampleExample To convert 21CTo convert 21C1616 to its decimal equivalent to its decimal equivalent
2 1 C
C X160 = 12 X 1 = 121 X161 = 1 X 16 = 16
2 X162 = 2 X 256= 512
540
1111
Computer Architecture
& Microprocessor
Conversion of Hexadecimal to Binary NumberConversion of Hexadecimal to Binary Number
The binary equivalent of each digit is usedThe binary equivalent of each digit is used
ExampleExample
To convert 5BTo convert 5B1616 to binary equivalent: to binary equivalent:
5 B5 B
010110110101101122
To convert B316 to binary equivalent:To convert B316 to binary equivalent: B 3B 3
101100111011001122
1212
Computer Architecture
& Microprocessor
Conversion of Binary to Decimal NumberConversion of Binary to Decimal Number
Sum of product of each digit with 2 raised to the power Sum of product of each digit with 2 raised to the power of positional value of positional value
Example:Example:
To find the decimal equivalent of 1011To find the decimal equivalent of 10112 2 ::
1313
Computer Architecture
& Microprocessor
Conversion from Octal to DecimalConversion from Octal to Decimal
Multiply the digits of the number by the powers of 8 and addMultiply the digits of the number by the powers of 8 and add
ExampleExample To convert 215To convert 21588 to its decimal equivalent to its decimal equivalent
2 1 5
5 X 80 = 5 X 1 = 51 X 81 = 1 X 8 = 8
2 X 82 = 2 X 64= 128
141
1414
Computer Architecture
& Microprocessor
9’s Complement9’s Complement
Difference of each digit of a number from 9Difference of each digit of a number from 9
Example:Example:
To find 9’s complement of To find 9’s complement of 5454 : :
9 99 9
5 45 4
4 54 5
1515
Computer Architecture
& Microprocessor
10’s Complement10’s Complement
Equivalent to the negative of a numberEquivalent to the negative of a number
Obtained by adding 1 to the 9’s complement of a numberObtained by adding 1 to the 9’s complement of a number
Example:Example:
To find 10’s complement of 54To find 10’s complement of 54= 9’s complement of 54 + 1 = 9’s complement of 54 + 1 = 45 + 1= 45 + 1= = 4646
1616
Computer Architecture
& Microprocessor
1’s Complement of binary number1’s Complement of binary number
Similar to 9’s complement of decimal numberSimilar to 9’s complement of decimal number
Obtained by subtracting each digit from 1Obtained by subtracting each digit from 1
ExampleExample
To find 1’s complement of 101To find 1’s complement of 101
1 1 11 1 11 0 11 0 10 1 00 1 0
1717
Computer Architecture
& Microprocessor
2’s complement of a binary number2’s complement of a binary number
Equivalent to 10’s complement of a decimal numberEquivalent to 10’s complement of a decimal number
Represents the negative equivalent of that numberRepresents the negative equivalent of that number
ExampleExample
To find the 2’s complement of 1010To find the 2’s complement of 1010= 1’s complement of 1010 + 1= 1’s complement of 1010 + 1= 0101 + 1= 0101 + 1= = 01100110
1818
Computer Architecture
& Microprocessor
Binary SubtractionBinary Subtraction
To subtract To subtract 1010 1010 from from 11001100
Find 2’s complement of 1010Find 2’s complement of 1010 Number Number : 1010: 1010
1’s complement1’s complement : 0101: 01012’s complement2’s complement : 0110: 0110
Add 2’s complement of 1010 with 1100Add 2’s complement of 1010 with 1100110011000110011000100010
1919
Computer Architecture
& MicroprocessorBCDBCD
Each digit is represented by four bits Each digit is represented by four bits
Decimal NumberDecimal Number BCDBCD
88 0000100000001000
99 0000100100001001
1010 0001000000010000
1111 0001000100010001
1212 0001001000010010
1313 0001001100010011
1414 0001010000010100
1515 0001010100010101
Decimal NumberDecimal Number BCDBCD
00 00000000
11 00010001
22 00100010
33 00110011
44 01000100
55 01010101
66 01100110
77 01110111
2020
Computer Architecture
& Microprocessor
Gray CodeGray Code
Only one bit changes for each consecutive numbersOnly one bit changes for each consecutive numbers
Decimal NumberDecimal Number Gray CodeGray Code
88 11001100
99 11011101
1010 11111111
1111 11101110
1212 10101010
1313 10111011
1414 10011001
1515 10001000
Decimal NumberDecimal Number Gray CodeGray Code
00 00000000
11 00010001
22 00110011
33 00100010
44 01100110
55 01110111
66 01010101
77 01000100
2121
Computer Architecture
& Microprocessor
ASCII CodesASCII Codes
American Standard Code for Information InterchangeAmerican Standard Code for Information Interchange
7 bit code7 bit code
Represents upto 128 charactersRepresents upto 128 characters
First 3 bits-zone bitsFirst 3 bits-zone bits
Second 4 bits-numeric bitsSecond 4 bits-numeric bits
2222
Computer Architecture
& MicroprocessorASCII CodesASCII Codes
ASCII Code Character
00 NUL
01 SOH
02 STX
03 ETX
04 EOT
05 ENQ
06 ACK
07 BEL
08 BS
09 HT
0A LF
0B VT
0C FF
0D CR
0E S1
0F S0
10 DLE
ASCII Code Character
11 DC1 (X-on)
12 DC2 (Tape)
13 DC3 (X-off)
14 DC4
15 NAK
16 SYN
17 ETB
18 CAN
19 EM
1A SUB
1B ESC
1C FS
1D GS
1E RS
1F US
20 SP
21 !
2323
Computer Architecture
& Microprocessor
ASCII CodeASCII Code
ASCII Code Character
22 “
23 #
24 $
25 %
26 &
27 ‘
28 (
29 )
2A *
2B +
2C ,
2D -
2E .
2F /
30 0
31 1
ASCII Code Character
32 2
33 3
34 4
35 5
36 6
37 7
38 8
39 9
3A :
3B ;
3C <
3D =
3E >
3F ?
40 @
41 A
2424
Computer Architecture
& Microprocessor
ASCII Code Character
42 B
43 C
44 D
45 E
46 F
47 G
48 H
49 I
4A J
4B K
4C L
4D M
4E N
4F O
50 P
51 Q
52 R
53 S
54 T
55 U
ASCII Characters
56 V
57 W
58 X
59 Y
5A Z
5B [
5C \
5D ]
5E ^ ( )
5F - ( )
61 a
62 b
63 c
64 d
65 e
66 f
67 g
69 h
6A i
6B j
2525
Computer Architecture
& MicroprocessorASCII Code Character
6B k
6C l
6D m
6E n
6F o
70 p
71 q
72 r
73 s
74 t
75 u
76 v
77 w
78 x
79 y
7A z
7B {
7C |
7D }
7E ~
7F DEL
2626
Computer Architecture
& Microprocessor
ASCII -8 CodeASCII -8 Code
Uses 8 bit codeUses 8 bit code
Represents upto 256 charactersRepresents upto 256 characters
First 4 bits-zone bitsFirst 4 bits-zone bits
Second 4 bits-numeric bitsSecond 4 bits-numeric bits
2727
Computer Architecture
& Microprocessor
Logic GatesLogic Gates
NOT gateNOT gate or Inverter or Inverter
output is opposite of inputoutput is opposite of input
Truth TableTruth Table I/P 0/PI/P 0/P 0 10 1 1 0 1 0
I/P O/P
2828
Computer Architecture
& Microprocessor
AND GateAND Gate
Truth TableTruth TableI/P1 I/P1 I/P2I/P2 O/P O/P 00 0 0 0 0 0 0 1 1 0 0 1 1 0 0 0 0 1 1 1 1 1 1
I/P1
I/P2O/P
2929
Computer Architecture
& Microprocessor
NAND GateNAND Gate
Truth TableTruth TableI/P1 I/P1 I/P2I/P2 O/P O/P 00 0 0 1 1 0 0 1 1 1 1 1 1 0 0 1 1 1 1 1 1 0 0
I/P1
I/P2O/P
3030
Computer Architecture
& Microprocessor
OR GateOR Gate
Truth TableTruth Table
I/P1I/P1 I/P2I/P2 O/PO/P00 00 0000 11 1111 00 1111 11 11
I/P1
I/P2O/P
3131
Computer Architecture
& Microprocessor
NOR GateNOR Gate
Truth TableTruth Table
I/P1I/P1 I/P2I/P2 O/PO/P00 00 1100 11 0011 00 0011 11 00
I/P1
I/P2O/P
3232
Computer Architecture
& Microprocessor
XOR GateXOR Gate
Truth TableTruth Table
I/P1I/P1 I/P2I/P2 O/PO/P00 00 0000 11 1111 00 1111 11 00
I/P1
I/P2O/P
3333
Computer Architecture
& Microprocessor
XNOR GateXNOR Gate
Truth TableTruth Table
I/P1I/P1 I/P2I/P2 O/PO/P00 00 1100 11 0011 00 0011 11 11
I/P1
I/P2O/P
3434
Computer Architecture
& Microprocessor
Boolean AlgebraBoolean Algebra
Algebra of binary values(1 & 0)Algebra of binary values(1 & 0)
Types of operationsTypes of operations
OR (+)OR (+) AND ( . )AND ( . ) NOT (- or ‘ )NOT (- or ‘ )
Minimizes the basic circuits to perform digital operations Minimizes the basic circuits to perform digital operations
3535
Computer Architecture
& Microprocessor
Algebraic TheoremsAlgebraic Theorems
OR LawsOR Laws
• A + 0 = AA + 0 = A• A + 1 =1A + 1 =1 • A + A = AA + A = A• A + A = 1A + A = 1
AND LawsAND Laws
• A . 0 = 0A . 0 = 0• A . 1 = AA . 1 = A• A . A = AA . A = A• A . A = 0A . A = 0
3636
Computer Architecture
& Microprocessor
Laws of ComplementationLaws of Complementation
A = AA = A 1 = 01 = 0 0 = 1 0 = 1 If A=0, then A =1If A=0, then A =1 If A=1, then A = 0If A=1, then A = 0
Commutative LawsCommutative Laws
A + B = B + AA + B = B + A A .B = B .AA .B = B .A
Associative LawsAssociative Laws
(A + B) + C = A + (B + C) = A + B + C(A + B) + C = A + (B + C) = A + B + C (A.B).C = A.(B.C) = A.B.C(A.B).C = A.(B.C) = A.B.C
3737
Computer Architecture
& MicroprocessorDistributive LawsDistributive Laws
A . (B+C) = A .B + A .CA . (B+C) = A .B + A .C A + B.C = (A + B) . (A + C)A + B.C = (A + B) . (A + C)
Other ExpressionsOther Expressions
A + AB = AA + AB = A A . (A + B) = AA . (A + B) = A A + AB = A + BA + AB = A + B A . (A + B) = ABA . (A + B) = AB AB + AB = AAB + AB = A (A + B)(A + B) = A(A + B)(A + B) = A AB + AC = (A + C) . (A + B)AB + AC = (A + C) . (A + B) (A + B) ( A + C) = AC + AB(A + B) ( A + C) = AC + AB AB + AC + BC = AB + ACAB + AC + BC = AB + AC (A + B)(A + C)(B + C) = (A + B)(A + C)(A + B)(A + C)(B + C) = (A + B)(A + C)
3838
Computer Architecture
& Microprocessor
Half Adder
Has two inputs (the bits to be summed)
Has two outputs (the sum bit and the carry bit)
AB CD
00011011
00101001
3939
Computer Architecture
& Microprocessor
an bn cn
sn cn+1
0 0 0 0 0
0 0 1 1 0
0 1 0 1 0
0 1 1 0 1
1 0 0 1 0
1 0 1 0 1
1 1 0 0 1
1 1 1 1 1
Full Adder – Truth Table
4040
Computer Architecture
& Microprocessor 7 Segment LED Display
4141
Computer Architecture
& Microprocessor
4242
Computer Architecture
& Microprocessor
0 0 0 0 01 0 0 0 12 0 0 1 03 0 0 1 14 0 1 0 05 0 1 0 16 0 1 1 07 0 1 1 18 1 0 0 09 1 0 0 1
1 1 1 1 1 1 0 0 1 1 0 0 0 0 1 1 0 1 1 0 1 1 1 1 1 0 0 1 0 1 1 0 0 1 1 1 0 1 1 0 1 1 1 0 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 0 1 1
INPUTS
X Y Z W A B C D E F G
OUTPUT
LEGAL DIGITS
1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1
1 0 0 1 1 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1
ERROR
7 Segment LED Display– Truth Table
4343
Computer Architecture
& MicroprocessorTTL CircuitTTL Circuit
Stands for transistor - transistor logic. Stands for transistor - transistor logic.
Operates between cut-off and saturation.Operates between cut-off and saturation. Advantages:Advantages:
• SpeedSpeed• good fan – in and fan – out good fan – in and fan – out • easy interface with other digital circuitry easy interface with other digital circuitry
4444
Computer Architecture
& Microprocessor
Flip FlopFlip Flop
Stores a binary digitStores a binary digit
Stable till a signal switches itStable till a signal switches it
Types of Types of flip flopTypes of Types of flip flop
S-R flip flopS-R flip flop J-K flip flopJ-K flip flop D flip flopD flip flop T flip flopT flip flop
4545
Computer Architecture
& Microprocessor
RegistersRegisters
Group of flip-flopsGroup of flip-flops
Connected in parallelConnected in parallel
D flip-flop commonly usedD flip-flop commonly used
Shift RegisterShift Register
Shifts content unchangedShifts content unchanged
Temporary storageTemporary storage
Types:Types: Serial-in, serial-outSerial-in, serial-out Serial-in, parallel-outSerial-in, parallel-out Parallel in, serial-outParallel in, serial-out Parallel in, parallel outParallel in, parallel out
4646
Computer Architecture
& MicroprocessorCountersCounters
Counts no. of pulsesCounts no. of pulses
Modulus of CounterModulus of Counter
• Binary CounterBinary Counter• Decade CounterDecade Counter• Pre settable CounterPre settable Counter
Binary CounterBinary Counter
J
k
Q
Q
J
k
Q
Q
J
k
Q
Q
J
k
Q
Q
CLK
3 2 1 0
4747
Computer Architecture
& Microprocessor
Types of CountersTypes of Counters
Up CounterUp Counter Down CounterDown Counter Up-Down CounterUp-Down Counter Controlled CounterControlled Counter Ring CounterRing Counter
Synchronous
Asynchronous
4848
Computer Architecture
& MicroprocessorComputer LanguagesComputer Languages
Machine Language Machine Language
– – 0 and 10 and 1
Assembly Language Assembly Language
– – mnemonics mnemonics – – assembler assembler
High Level Language High Level Language
– – English like language English like language – – Interpreters and CompilersInterpreters and Compilers
4949
Computer Architecture
& Microprocessor
Execution of Assembly Language programExecution of Assembly Language program
Source Program
Assembler
Object Program
Loader
Floppy Disk
Floppy Disk
One to One Translation
5050
Computer Architecture
& Microprocessor
Execution of High Level LanguageExecution of High Level Language
Source Code
Translator
Object Code 1 Object Code 2 Object Code 3
One to Many Translation
5151
Computer Architecture
& Microprocessor
Compiler & InterpreterCompiler & Interpreter
Interpreter translates line by lineInterpreter translates line by line
- Slower- Slower
Compiler translates the entire codeCompiler translates the entire code
- faster- faster
52
Session IISession II
Microprocessor – an Introduction Microprocessor – an Introduction General Architecture of MicroprocessorGeneral Architecture of Microprocessor MemoryMemory I/OI/O Architecture of 8085 MicroprocessorArchitecture of 8085 Microprocessor
5353
Computer Architecture
& MicroprocessorMicroprocessor – An Microprocessor – An IntroductionIntroduction
Programmable Logical device Programmable Logical device
FunctionalityFunctionality
• manipulates data manipulates data • Controls timing of various operationsControls timing of various operations• communicates with peripheralscommunicates with peripherals
ApplicationsApplications
• Automation & ControlAutomation & Control
5454
Computer Architecture
& MicroprocessorArchitecture & Operations of Architecture & Operations of MPUMPU Architecture Architecture
- Logical design of microprocessor- Logical design of microprocessor
Types of OperationsTypes of Operations
• Microprocessor initiated operationsMicroprocessor initiated operations
• Internal Data OperationsInternal Data Operations
• Peripheral initiated OperationPeripheral initiated Operation
5555
Computer Architecture
& MicroprocessorMicroprocessor initiated Microprocessor initiated operationsoperations
Communications OperationsCommunications Operations
• Memory ReadMemory Read• Memory WriteMemory Write• I/O ReadI/O Read• I/O WriteI/O Write
Steps involvedSteps involved
• Location IdentificationLocation Identification• Transfer of dataTransfer of data• Providing Timing or synchronization signalsProviding Timing or synchronization signals
5656
Computer Architecture
& Microprocessor
RequirementRequirement
Address BusAddress Bus
• UnidirectionalUnidirectional• Arbitrary number – (commonly used 16)Arbitrary number – (commonly used 16)• Capable of Addressing 2 Capable of Addressing 2 nn
Data BusData Bus
• BidirectionalBidirectional• Decides the range of data being handledDecides the range of data being handled• Determines the word length and the register sizeDetermines the word length and the register size
5757
Computer Architecture
& Microprocessor
Control BusControl Bus
• A number of Single linesA number of Single lines• Provides timing signalsProvides timing signals
Communication ProcessCommunication Process
To Read an instructionTo Read an instruction
• Location is identified by placing the address in Address BusLocation is identified by placing the address in Address Bus• A pulse for initiating a READ is sentA pulse for initiating a READ is sent• Data Bus brings the data to MPUData Bus brings the data to MPU
5858
Computer Architecture
& MicroprocessorInternal Data Operations
Processing of Data and its StorageProcessing of Data and its Storage
• Arithmetic & Logical OperationArithmetic & Logical Operation• Condition TestingCondition Testing• Order of ExecutionOrder of Execution• Storing of DataStoring of Data
RequirementRequirement
• AccumulatorAccumulator• Flag RegisterFlag Register• General purpose RegistersGeneral purpose Registers• Program CounterProgram Counter• StackStack
5959
Computer Architecture
& Microprocessor
(8085 Microprocessor)(8085 Microprocessor)
AccumulatorAccumulator
• Performs Arithmetic and logical OperationsPerforms Arithmetic and logical Operations• 8 bit Register8 bit Register
Flag RegisterFlag Register
• Used for Decision MakingUsed for Decision Making• 5 Flags – Carry, Zero, Auxiliary Carry, Sign, Parity5 Flags – Carry, Zero, Auxiliary Carry, Sign, Parity
Program Status WordProgram Status Word
6060
Computer Architecture
& Microprocessor
RegistersRegisters
• Stores Data during ExecutionStores Data during Execution• 6 8-bit registers – B, C, D, E, H and L6 8-bit registers – B, C, D, E, H and L• Register Combination – BC, DE and HLRegister Combination – BC, DE and HL
Program Counter (PC)Program Counter (PC)
• 16 Bit Memory Pointer16 Bit Memory Pointer• Sequences the ExecutionSequences the Execution
Stack Pointer (SP)Stack Pointer (SP)
• 16 Bit Memory Pointer16 Bit Memory Pointer• Points to location in R/W MemoryPoints to location in R/W Memory
6161
Computer Architecture
& Microprocessor
Peripheral initiated OperationPeripheral initiated Operation
Operations initiated by external devicesOperations initiated by external devices
ResetReset• Program Counter is clearedProgram Counter is cleared
InterruptInterrupt• Normal Execution interrupted to execute Service RoutineNormal Execution interrupted to execute Service Routine
ReadyReady• Synchronizes MPU operations with PeripheralsSynchronizes MPU operations with Peripherals
HoldHold• Peripherals takes Control of BusesPeripherals takes Control of Buses
6262
Computer Architecture
& Microprocessor
MemoryMemory
Stores Binary ValuesStores Binary Values
TypesTypes
• Read Write Memory (R/W M)Read Write Memory (R/W M)• Read Only Memory (ROM)Read Only Memory (ROM)
R/W Memory (Random Access Memory)R/W Memory (Random Access Memory)• VolatileVolatile• processes data processes data • Types:- Types:- Static & DynamicStatic & Dynamic
6363
Computer Architecture
& Microprocessor
Static R/W MemoryStatic R/W Memory
• Flip-flopsFlip-flops• Stored as VoltageStored as Voltage
Dynamic R/W MemoryDynamic R/W Memory
• MOS Transistor MOS Transistor • Stored as chargesStored as charges• FasterFaster• Refreshing CircuitRefreshing Circuit
6464
Computer Architecture
& Microprocessor
ROM MemoryROM Memory
• Non VolatileNon Volatile
• Used for subroutinesUsed for subroutines
• Cheap & DenseCheap & Dense
• Types: - Types: -
Masked ROM Masked ROM PROM (Programmable Read Only Memory)PROM (Programmable Read Only Memory) EPROM (Erasable Programmable Read Only Memory)EPROM (Erasable Programmable Read Only Memory) EEPROM (Electrically Erasable PROM)EEPROM (Electrically Erasable PROM)
6565
Computer Architecture
& Microprocessor
Memory OrganizationMemory Organization
A memory requires:A memory requires:
• Chips containing Registers Chips containing Registers • Chip Select lineChip Select line• R/W lineR/W line• Address linesAddress lines• I/O linesI/O lines
Memory MapMemory Map
• Assigning a unique address for each registerAssigning a unique address for each register
6666
Computer Architecture
& Microprocessor
Control LogicADDRESS
DECODER
R/W
D7 D6 D5 D4 D3 D2 D1 D0
A2
A1
A0
110
110
101
100
011
010
001
000
Size of MemorySize of Memory• Number of RegisterNumber of Register• Number of I/O linesNumber of I/O lines
CS
6767
Computer Architecture
& Microprocessor
Input / OutputInput / Output
• Communicates to the external worldCommunicates to the external world
Methods of CommunicationMethods of Communication
• Peripheral or Direct I/OPeripheral or Direct I/O
• Memory-Mapped I/OMemory-Mapped I/O
6868
Computer Architecture
& Microprocessor
• Peripheral or Direct I/OPeripheral or Direct I/O IN/OUTIN/OUT Transfers data Transfers data 8 Address Lines - 256 devices – Port Numbers8 Address Lines - 256 devices – Port Numbers Uses Control Lines – IOW & IORUses Control Lines – IOW & IOR
• Memory-Mapped I/OMemory-Mapped I/O
16 Address Lines 16 Address Lines Memory Map is sharedMemory Map is shared Uses Control Lines – MEMW & MEMRUses Control Lines – MEMW & MEMR
6969
Computer Architecture
& Microprocessor
Interfacing DevicesInterfacing Devices
Tri-State DeviceTri-State Device• 3 stages – logic 1, logic 0 and high impedance3 stages – logic 1, logic 0 and high impedance
BufferBuffer• Logic circuit which amplifies the currentLogic circuit which amplifies the current
LatchLatch• a D flip-flopa D flip-flop• Types :-Types :-
D
G
Q
Q
Transparent Latch Positive Edge Triggered
D
CK
Q
Q
PR
CLR
7070
Computer Architecture
& Microprocessor
DecoderDecoder• Displays an output based on the Displays an output based on the
combination of inputcombination of input
EncoderEncoder• Outputs a code based on the inputOutputs a code based on the input
2 to 4Decoder
2 to 4Encoder
Output
Output
Input
Input
7171
Computer Architecture
& Microprocessor
8085 Microprocessor8085 Microprocessor
FeaturesFeatures
• 8 bit8 bit• Has 40 pinsHas 40 pins• Multiplexed Address/ Data BusMultiplexed Address/ Data Bus
7272
Computer Architecture
& Microprocessor8085
PINOUTX1
X2
RESET OUT
SOD
SID
TRAP
RST 7.5
RST 6.5
RST 5.5
INTR
INTA
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
VSS
Vcc
HOLD
HLDA
CLK(OUT)
RESET IN
READY
IO/M
S1
RD
WR
ALE
S0
A15
A14
A13
A12
A11
A10
A9
A8
1
2
3
4
5
6
7
8
9
10
11
12
14
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
7373
Computer Architecture
& Microprocessor+5V GND
Serial
I/O
Ports
Interrupts
&
Externally
Initiated
Signals
External Signal
Acknowledgement
RESET CLK OUTOUT
X1 X2 Vcc Vss
ALE
S0
S1
IO/M
RD
WR
SID
SOD
TRAP
RST 7.5
RST 6.5
RST 5.5
INTR
READY
HOLD
RESET IN
INTA
HLDA
High-OrderAddress Bus
MultiplexedAddress/Data Bus
A15
A8
AD7
AD0
Control
And
Status Signals
8085 Signals
7474
Computer Architecture
& Microprocessor
8085 Microprocessor Signal Groups8085 Microprocessor Signal Groups
Address BusAddress Bus
• UniDirectionalUniDirectional• 8 Higher Order Address Bus8 Higher Order Address Bus
Multiplexed Address/Data BusMultiplexed Address/Data Bus
• BiDirectionalBiDirectional• Bus MultiplexingBus Multiplexing• Latching of Low - order Address Bus – ALE Latching of Low - order Address Bus – ALE
7575
Computer Architecture
& Microprocessor
Control and Status SignalControl and Status Signal
ALE (Address Latch Enable)ALE (Address Latch Enable)• Generated in the beginning of each operationGenerated in the beginning of each operation• Latches low - order address from the multiplexed busLatches low - order address from the multiplexed bus
RD (Read)RD (Read)• Active low Control SignalActive low Control Signal• Reads from Memory / IOReads from Memory / IO
WR (Write)WR (Write)• Active low Control SignalActive low Control Signal• Writes to selected Memory / IOWrites to selected Memory / IO
7676
Computer Architecture
& Microprocessor
IO/M
RD
8085
WR
A15
A8
ALE
AD7
AD0
ENLATCH
A15
A8
A7
A0
D7
D0
Data Bus
MEMR
MEMW
IOR
IOW
Control Signals
7777
Computer Architecture
& Microprocessor
IO/MIO/M
• High – IO OperationHigh – IO Operation• Low – Memory OperationLow – Memory Operation
SS11 and S and S00
• Status Signal – rarely usedStatus Signal – rarely used• Identifies various operationsIdentifies various operations
S1S1 So Desc. So Desc.0 0 0 0 HALT HALT0 0 1 1 WRITE WRITE1 1 0 0 READ READ11 1 1 FETCH FETCH
7878
Computer Architecture
& Microprocessor
Power Supply and Clock FrequencyPower Supply and Clock Frequency
• +5V power supply (Vcc)+5V power supply (Vcc)• 3 MHz clock (X1 & X2)3 MHz clock (X1 & X2)• CLK – Used as System Clock for other devicesCLK – Used as System Clock for other devices
Interrupts and Externally Initiated OperationsInterrupts and Externally Initiated Operations
• Interrupts transfer the program control to specific memory Interrupts transfer the program control to specific memory locationlocation
INTR (Interrupt Request)INTR (Interrupt Request)• A general-purpose interruptA general-purpose interrupt..
INTA (Interrupt Acknowledge)INTA (Interrupt Acknowledge)• Acknowledges an interruptAcknowledges an interrupt
7979
Computer Architecture
& Microprocessor
RST 7.5 (Restart Interrupt)RST 7.5 (Restart Interrupt)• Highest priority Vectored InterruptHighest priority Vectored Interrupt
RST 6.5 (Restart Interrupt)RST 6.5 (Restart Interrupt)• Vectored interrupt with a priority less than RST 7.5, but Vectored interrupt with a priority less than RST 7.5, but
more than RST 5.5 and INTR.more than RST 5.5 and INTR.
RST 5.5 (Restart Interrupt)RST 5.5 (Restart Interrupt)• Vectored interrupt with the least priority among Restart Vectored interrupt with the least priority among Restart
Interrupts but more priority than INTR signals.Interrupts but more priority than INTR signals.
TRAP (Input)TRAP (Input)• A non-maskable restart interrupt. A non-maskable restart interrupt. • highest priority of any interrupt.highest priority of any interrupt.
• Externally initiated signals are instantiated by an external Externally initiated signals are instantiated by an external device device
8080
Computer Architecture
& Microprocessor HOLDHOLD
• Indicates a peripheral’s request to use address and data Indicates a peripheral’s request to use address and data buses. buses.
HLDA ( Hold Acknowledge)HLDA ( Hold Acknowledge)• Acknowledges the HOLD request. Acknowledges the HOLD request.
READYREADY• Delays microprocessor’s operation to work in pace with the Delays microprocessor’s operation to work in pace with the
slow peripherals connected to it. slow peripherals connected to it.
RESET INRESET IN• Sets program counter to zero Sets program counter to zero • The buses are tri-stated and MPU is reset.The buses are tri-stated and MPU is reset.
RESET OUTRESET OUT• Indicates MPU is being reset Indicates MPU is being reset • Can be used to reset other devices.Can be used to reset other devices.
8181
Computer Architecture
& Microprocessor
Serial I/O PortsSerial I/O Ports
SID (Input)SID (Input)
• Serial input data Line Serial input data Line • The data on SID is loaded into accumulator when a RIM The data on SID is loaded into accumulator when a RIM
instruction is executed.instruction is executed.
SOD (output)SOD (output)
• Serial output data line. Serial output data line. • The output SOD is set or reset as specified by the SIM The output SOD is set or reset as specified by the SIM
instruction.instruction.
8282
Computer Architecture
& Microprocessor
Address Buffer
Accumulator (8)
Temp Reg. (8)
Arithmetic Logic Unit
(ALU)
(8)
Instruction Decoder
and Machine
Cycle Encoding
Flag (5)
Flip-flops
Instruction Register (8)
W Temp. Reg. Z Temp. Reg.
B Reg.
D Reg.
H Reg.
Stack
Program Counter
C Reg.
E Reg.
L Reg.
Address Latch (16)
Data Address Buffer (8)
Multiplexer
Timing and ControlCLK ResetGEN Control Status DMA
Re
g.
Se
lec
t
Serial I/O Control
SID
Interrupt Control
TRAPRST 7.5
RST 6.5RST 5.5
INTA INTR
SOD
ReadyRD WR ALE S0 S1 IO/M HLDA RESET OUT
RESET INHOLDA15 – A8
Address Bus AD7 – AD0
Address/Data Bus
X1
x2
Register Array
8383
Computer Architecture
& Microprocessor
RegistersRegisters
A A (Accumulato(Accumulato
r) r)
8 Bits8 Bits
Arithmetic OperationsArithmetic Operations
Logical OperationsLogical Operations
BB
8 8 BitsBits
CC
8 Bits8 BitsB & C combined to form 16 B & C combined to form 16 BitsBits
DD
8 8 BitsBits
EE
8 Bits8 BitsD & E combined to form 16 D & E combined to form 16 BitsBits
HH
8 8 BitsBits
LL
8 Bits8 BitsH & L combined to form 16 H & L combined to form 16 BitsBits
PC (Program PC (Program Counter)Counter)
16 Bits16 Bits
Has the Program Pointer Has the Program Pointer AddressAddress
SP (Stack SP (Stack Pointer)Pointer)
16 Bits16 Bits
Has the Memory Pointer Has the Memory Pointer AddressAddress
8484
Computer Architecture
& Microprocessor
FlagsFlags
SS ZZ ACAC PP CYCY D7 D6 D5 D4 D3 D2 D1 D0
SS SignSign Set – PositiveSet – Positive
Reset – NegativeReset – Negative
ZZ ZeroZero Set – ZeroSet – Zero
Reset – Non-ZeroReset – Non-Zero
AACC
AuxilAuxiliary iary CarrCarr
yy
Set – Carry From D3 to Set – Carry From D3 to D4D4
Reset – No Carry From Reset – No Carry From D3 to D4D3 to D4
PP ParitParityy
Set – EvenSet – Even
Reset – Odd Reset – Odd
CCYY
CarrCarryy
Set – Carry ExistsSet – Carry Exists
Reset – No Carry existsReset – No Carry exists
8585
Computer Architecture
& Microprocessor
Bus TimingsBus Timings
• Sequence of operations called instruction Sequence of operations called instruction cycle executes an instruction cycle executes an instruction
• Instruction Cycle is divided into few basic Instruction Cycle is divided into few basic machine cyclesmachine cycles
• Machine cycles are in turn divided into Machine cycles are in turn divided into System Clock Period.System Clock Period.
Example:Example:• To fetch a data 10101010 from a location To fetch a data 10101010 from a location
2005H2005H
8686
Computer Architecture
& Microprocessor
T1 T2 T3
CLK
A15 – A8
AD7 –AD0
ALE
IO/M
RD
Low -Order
Memory Address
Memory
Contents
M
High –Order
Memory Address
8787
Computer Architecture
& Microprocessor
ALUInstruction
Decoder
ControlLogic
B
D
H
Stack
Program Counter
C
E
L
Address Bus
Data Bus
Memory
8888
Computer Architecture
& Microprocessor
Instruction Set of 8085Instruction Set of 8085
Instruction Instruction • A command to perform a given task. A command to perform a given task. • A binary pattern designed inside a microprocessor to A binary pattern designed inside a microprocessor to
perform a specific function on a specified data. perform a specific function on a specified data.
Instruction SetInstruction Set• Entire group of instructions that determines what Entire group of instructions that determines what
functions the microprocessor can perform. functions the microprocessor can perform.
Parts of Instruction: Parts of Instruction: • Task to be performed – operation code (opcode)Task to be performed – operation code (opcode)• Data to be operated on – operand. Data to be operated on – operand.
8989
Computer Architecture
& Microprocessor
ClassificationClassification• Instruction Word Size Instruction Word Size
One-word or 1-byte instructionsOne-word or 1-byte instructions Two-word or 2-byte instructionsTwo-word or 2-byte instructions Three-word or 3-byte instructionsThree-word or 3-byte instructions
• FunctionalityFunctionality Data transfer (copy) operationsData transfer (copy) operations Arithmetic operationsArithmetic operations Logical operationsLogical operations Branching operationsBranching operations Machine-control operations. Machine-control operations.
9090
Computer Architecture
& Microprocessor
ONE-BYTE INSTRUCTIONSONE-BYTE INSTRUCTIONS
• Includes opcode and operand in single byte.Includes opcode and operand in single byte.• Operand(s) are internal registerOperand(s) are internal register
Example:Example:• MOV C,AMOV C,A
Both operand registers are specified.Both operand registers are specified.
• ADD BADD B The operand B is specified and the accumulator is The operand B is specified and the accumulator is
assumed. assumed.
• CMA CMA Accumulator is assumed to be the implicit operand Accumulator is assumed to be the implicit operand
9191
Computer Architecture
& Microprocessor
TWO-BYTE INSTRUCTIONSTWO-BYTE INSTRUCTIONS
• Uses two-bytes Uses two-bytes First byte specifies the operation code First byte specifies the operation code Second byte specifies the operand. Second byte specifies the operand. Source operand is a data byteSource operand is a data byte
• ExampleExample MVI A, 32HMVI A, 32H
THREE-BYTE INSTRUCTIONTHREE-BYTE INSTRUCTION
• First byte specifies the opcodeFirst byte specifies the opcode• Following two bytes specify the 16-bit address. Following two bytes specify the 16-bit address.
second byte – low-order address or datasecond byte – low-order address or data third byte is the high-order address or datathird byte is the high-order address or data
• ExampleExample JMP 2085H, LXI H, 2050HJMP 2085H, LXI H, 2050H
9292
Computer Architecture
& Microprocessor
DATA TRANSFER (COPY) OPERATIONSDATA TRANSFER (COPY) OPERATIONS
• Copies data from a location called a source to Copies data from a location called a source to another location called a destinationanother location called a destination
• Contents of source not modifiedContents of source not modified
• Types of data transfer :Types of data transfer :
Between Registers.Between Registers. Specific data byte to a register or a memory location.Specific data byte to a register or a memory location. Between a memory location and a registerBetween a memory location and a register
Between an I/O device and the accumulator.Between an I/O device and the accumulator.
9393
Computer Architecture
& Microprocessor
MOVMOV• Copies data from one register to anotherCopies data from one register to another• Syntax:Syntax:
MOV RMOV Rdd, R, Rss
• Example:Example: MOV A, BMOV A, B
MVIMVI• Copies 8 Bit data to a specific registerCopies 8 Bit data to a specific register• Syntax:Syntax:
MVI Rd, DMVI Rd, D
• Example:Example: MVI C, 5MVI C, 5
9494
Computer Architecture
& Microprocessor
OUTOUT• Copies the Contents of Accumulator to PortCopies the Contents of Accumulator to Port• Syntax:Syntax:
OUT PortNo.OUT PortNo.
• Example:Example: OUT 56OUT 56
ININ• Copies the Contents of the Port to AccumulatorCopies the Contents of the Port to Accumulator• Syntax:Syntax:
IN PortNo.IN PortNo.
• Example:Example: IN 57IN 57
9595
Computer Architecture
& Microprocessor
Between RegistersBetween Registers
OP OP CodeCode
OperOperandand
BytByteses
DescriptionDescription
MOVMOV Rd, Rd, RsRs
11 Copies data From Copies data From Source Register Source Register RsRs to to Destination Register Destination Register RdRdOP OP
CodeCodeOperOperandand
BytesBytes DescriptionDescription
MOVMOV M, RsM, Rs 11 Copies data From Copies data From Source Register Source Register RsRs to Memory to Memory MM
MOVMOV Rd, Rd, MM
11 Copies data From Copies data From memory memory MM to to Destination Destination Register Register RdRd
Between Registers and MemoryBetween Registers and Memory
9696
Computer Architecture
& MicroprocessorData to/from Register, Memory Data to/from Register, Memory or I/O Portor I/O PortOP OP
CodeCodeOperOperandand
BytByteses
DescriptionDescription
ININ 8 Bit 8 Bit Port Port AddrAddressess
22 Copies data From Copies data From Specified port Address Specified port Address to Accumulator to Accumulator AA
OUTOUT 8 Bit 8 Bit Port Port AddrAddressess
22 Copies data From Copies data From Accumulator Accumulator AA to to Specified port AddressSpecified port Address
MVIMVI R, R, Data Data (8 (8 Bits)Bits)
22 Loads the Data to the Loads the Data to the Specified RegisterSpecified Register
LHLDLHLD 16 16 Bit Bit AddrAddressess
33 Copies the content of Copies the content of the memory location the memory location pointed out by 16 bit pointed out by 16 bit address to Register address to Register LL and content of next and content of next memory location to memory location to Register Register HH
SHLDSHLD 16 16 Bit Bit AddrAddressess
33 Copies the content of Copies the content of the Register the Register LL to to memory location memory location pointed out by 16 bit pointed out by 16 bit address and content of address and content of Register Register HH to next to next memory locationmemory location
9797
Computer Architecture
& Microprocessor
OP OP CodeCode
OperOperandand
BytByteses
DescriptionDescription
LDALDA 16 16 Bit Bit AddrAddressess
33 Copies the content of Copies the content of Memory location Memory location specified by 16 bit specified by 16 bit address to Accumulator address to Accumulator AA
LDAXLDAX RP RP B/DB/D
11 Copies the content of Copies the content of Memory Location Memory Location Specified in Register Pair Specified in Register Pair B or DB or D to Accumulator to Accumulator A A
STASTA 16 16 Bit Bit AddrAddressess
33 Copies the content of Copies the content of Accumulator Accumulator AA to to Memory location Memory location specified by 16 bit specified by 16 bit addressaddress
STAXSTAX RP RP B/DB/D
11 Copies the content of Copies the content of Memory Location Memory Location AccumulatorAccumulator A A to to Specified in Register Pair Specified in Register Pair B or DB or D
LXILXI RP, RP, 16 16 Bit Bit DataData
33 Loads the 16 bit data Loads the 16 bit data into the Register Pair into the Register Pair
XCHXCHGG
NoneNone 11 Contents of Register Contents of Register HH is is exchanged with Register exchanged with Register DD and Contents of and Contents of Register Register LL is exchanged is exchanged with Register with Register EE
Data to/from Register, Data to/from Register, Memory or I/O PortMemory or I/O Port
9898
Computer Architecture
& Microprocessor
ARITHMETIC OPERATIONSARITHMETIC OPERATIONS
• Performs addition, subtraction, increment and decrement.Performs addition, subtraction, increment and decrement.
Addition Addition • Adds an 8-bit data to the accumulatorAdds an 8-bit data to the accumulator• Carry Flag is set if the sum exceeds 8-bitsCarry Flag is set if the sum exceeds 8-bits
ADDADD• Adds a register’s content to the accumulatorAdds a register’s content to the accumulator• Syntax:Syntax:
ADD RADD R
ADIADI• Adds an 8-bit data to the accumulatorAdds an 8-bit data to the accumulator• Syntax:Syntax:
ADI 8-bit DataADI 8-bit Data
9999
Computer Architecture
& Microprocessor
Subtraction Subtraction
• Subtracts an 8-bit data to the accumulator and the Subtracts an 8-bit data to the accumulator and the stores the difference in it.stores the difference in it.
• Performed in 2's complement methodPerformed in 2's complement method
SUBSUB• Subtracts a register’s content from the accumulatorSubtracts a register’s content from the accumulator• Syntax:Syntax:
SUB RSUB R
SUISUI• Subtracts an 8-bit data from the accumulatorSubtracts an 8-bit data from the accumulator• Syntax:Syntax:
SBI 8-bit DataSBI 8-bit Data
100100
Computer Architecture
& Microprocessor
Increment/Decrement Increment/Decrement
• Increments/Decrements 8-bit content by 1. Increments/Decrements 8-bit content by 1. • Increments/Decrements 16-bit contents of a register pair Increments/Decrements 16-bit contents of a register pair
(such as BC)(such as BC)
INRINR• Increments the content of a registerIncrements the content of a register• Syntax:Syntax:
INR B INR B
DCRDCR• Decrements the content of a registerDecrements the content of a register• Syntax:Syntax:
DCR BDCR B
101101
Computer Architecture
& Microprocessor
Arithmetic OperationsArithmetic OperationsOP OP
CodeCodeOpeOperandrand
BytByteses
DescriptionDescription
ADDADD R/MR/M 11 Content of the Content of the Register Register or Memory or Memory is added to is added to the content of the content of Accumulator Accumulator and the and the result is stored in result is stored in AccumulatorAccumulator
SUBSUB R/MR/M 11 Content of the Content of the Register Register or Memory or Memory is subtracted is subtracted from the content of from the content of Accumulator Accumulator and the and the result is stored in result is stored in AccumulatorAccumulator
ADIADI 8 Bit 8 Bit DataData
22 8 Bit Data 8 Bit Data is added to is added to the the AccumulatorAccumulator content content and stores the result in and stores the result in AccumulatorAccumulator
SUISUI 8 Bit 8 Bit DataData
22 8 Bit Data 8 Bit Data is subtracted is subtracted from the content of from the content of Accumulator Accumulator and the and the result is stored in result is stored in AccumulatorAccumulator
INRINR R/MR/M 11 The content of the The content of the specified specified Register or Register or MemoryMemory is is incrementedincremented by by 11
DCRDCR R/MR/M 11 The content of the The content of the specified specified Register or Register or MemoryMemory is is decrementeddecremented by by 11
102102
Computer Architecture
& Microprocessor
LOGICAL OPERATIONSLOGICAL OPERATIONS
• Performs logical operations with accumulator contentPerforms logical operations with accumulator content
AND, OR, Exclusive-OR AND, OR, Exclusive-OR
• Performed on an 8-bit data and accumulator content Performed on an 8-bit data and accumulator content
ANDAND• Logically AND the Register Content with Accumulator Logically AND the Register Content with Accumulator
ContentContent• Syntax:Syntax:
AND RAND R ANIANI
• Logically ANd Immediately 8-Bit Data with Accumulator Logically ANd Immediately 8-Bit Data with Accumulator ContentContent
• Syntax:Syntax: ANI 14ANI 14
103103
Computer Architecture
& Microprocessor
ORAORA
• Logically OR contents of Register with AccumulatorLogically OR contents of Register with Accumulator
• Syntax:Syntax: ORA CORA C
ORIORI
• Logically OR Immediately 8 Bit Data with AccumulatorLogically OR Immediately 8 Bit Data with Accumulator
• Syntax:Syntax: ORI DORI D
104104
Computer Architecture
& Microprocessor
XRAXRA
• Logically Exclusive - OR the contents of Register with Logically Exclusive - OR the contents of Register with AccumulatorAccumulator
• Syntax:Syntax: XRA CXRA C
XRIXRI
• Logically Exclusively - OR immediately 8 Bit Data with Logically Exclusively - OR immediately 8 Bit Data with AccumulatorAccumulator
• Syntax:Syntax: XRI 6XRI 6
105105
Computer Architecture
& Microprocessor
CMACMA
• Complements the contents of accumulatorComplements the contents of accumulator• No Flags are affectedNo Flags are affected• Syntax:Syntax:
CMACMA
RotateRotate
• Shifts Shifts BitsBits in the accumulator either left or right in the accumulator either left or right
CompareCompare• Compares an 8-bit data with accumulator contentCompares an 8-bit data with accumulator content
106106
Computer Architecture
& Microprocessor BRANCHING OPERATIONSBRANCHING OPERATIONS
• Alters program execution sequence either conditionally Alters program execution sequence either conditionally or unconditionally.or unconditionally.
Jump Jump • Conditional jump Conditional jump
Alters program sequence when condition test is trueAlters program sequence when condition test is true
• Unconditional jumpUnconditional jump Alters program sequence without condition checkingAlters program sequence without condition checking
CallCall• Changes sequence of a program by calling a subroutine Changes sequence of a program by calling a subroutine
ReturnReturn• Changes sequence of a program by returning from a Changes sequence of a program by returning from a
subroutine subroutine
107107
Computer Architecture
& Microprocessor
Unconditional jumpUnconditional jump
JMPJMP
• The program control is transferred to a The program control is transferred to a particular memory addressparticular memory address
• Syntax:Syntax: JMP AddressJMP Address
• Example:Example: JMP F200JMP F200
108108
Computer Architecture
& Microprocessor Conditional JumpConditional Jump
• Based on Condition of the flagsBased on Condition of the flags• All Instructions are followed by a 16-Bit addressAll Instructions are followed by a 16-Bit address
JCJC• Transfers program control to a particular address if Carry Transfers program control to a particular address if Carry
Flag is SetFlag is Set
JNCJNC• Transfers program control to a particular address if Carry Transfers program control to a particular address if Carry
Flag is not SetFlag is not Set
JZJZ• Transfers program control if Zero Flag is SetTransfers program control if Zero Flag is Set
JNZJNZ• Transfers program control if Zero Flag is not SetTransfers program control if Zero Flag is not Set
109109
Computer Architecture
& Microprocessor
JPJP• Transfers program control if Sign Flag is not SetTransfers program control if Sign Flag is not Set
JMJM• Transfers program control if Sign Flag is SetTransfers program control if Sign Flag is Set
JPEJPE• Transfers program control if Parity Flag is SetTransfers program control if Parity Flag is Set
JPOJPO• Transfers program control if Parity Flag is not SetTransfers program control if Parity Flag is not Set
110110
Computer Architecture
& Microprocessor
MACHINE CONTROL OPERATIONSMACHINE CONTROL OPERATIONS• Controls machine functions Controls machine functions • Examples:Examples:
Halt, Interrupts, No OperationHalt, Interrupts, No Operation
HaltHalt• Processor Stops ExecutingProcessor Stops Executing• Syntax:Syntax:
HLTHLT
No OperationNo Operation• No Operation is performedNo Operation is performed• Syntax:Syntax:
NOPNOP
111111
Computer Architecture
& Microprocessor
8085 ADDRESSING MODES8085 ADDRESSING MODES
• Addressing Modes specifies various formats for operands Addressing Modes specifies various formats for operands
a register, an input/ output port, or an 8-bit numbera register, an input/ output port, or an 8-bit number
Types:Types:
• Immediate addressing.Immediate addressing.
• Register addressing.Register addressing.
• Direct addressing.Direct addressing.
• Indirect addressing.Indirect addressing.
112112
Computer Architecture
& Microprocessor
Immediate AddressingImmediate Addressing
• Data is present in the instruction Data is present in the instruction • Example:Example:
MVI R,dataMVI R,data
Register addressingRegister addressing
• Data is provided through the registers. Data is provided through the registers. • Example: Example:
MOV Rd, RsMOV Rd, Rs
113113
Computer Architecture
& Microprocessor
Direct addressingDirect addressing
• Accepts data from or sends data to the outside device. Accepts data from or sends data to the outside device.
• Example: Example: IN 00H or OUT 01HIN 00H or OUT 01H
Indirect AddressingIndirect Addressing
• Effective Address is calculated by the processorEffective Address is calculated by the processor
• The contents of the address (and the one following) is The contents of the address (and the one following) is used to form a second address where the data is used to form a second address where the data is storedstored
114114
Computer Architecture
& MicroprocessorAssembly Language Assembly Language ProgrammingProgramming
Memory AddressMemory Address• 16 bit address of System Memory16 bit address of System Memory
Machine CodeMachine Code• Hexadecimal entered in System MemoryHexadecimal entered in System Memory
OpcodeOpcode• Abbreviated Symbols specified by manufacturerAbbreviated Symbols specified by manufacturer
OperandOperand• Item to be processedItem to be processed
CommentsComments• Documentation explaining purpose of instructions usedDocumentation explaining purpose of instructions used
115115
Computer Architecture
& Microprocessor
Assembly Language ProgramAssembly Language Program
Program to accept and display a number Program to accept and display a number
TaskTask MnemonicsMnemonics
1.1. Load Register B with 4EHLoad Register B with 4EH MVI B, 4EHMVI B, 4EH
2.2. Copy the Number to AccumulatorCopy the Number to Accumulator MOV A, BMOV A, B
3.3. Sent the Number to Output PortSent the Number to Output Port OUT, Port1OUT, Port1
4.4. End of the ProgramEnd of the Program HLTHLT
116116
Computer Architecture
& Microprocessor
Programming FormatProgramming Format
OP OP CodeCode
OperaOperandnd
DescriptionDescription
MVIMVI B, B, 37H37H
Loads 37H to Register BLoads 37H to Register B
MOVMOV A, BA, B Copies Content of Register B Copies Content of Register B to Accumulatorto Accumulator
OUTOUT Port1Port1 Sends 37H to Port ‘Sends 37H to Port ‘Port1Port1’’
HLTHLT NoneNone End of the ProgramEnd of the Program
117117
Computer Architecture
& Microprocessor
Arithmetic OperationsArithmetic OperationsOP OP CodeCode
OperOperandand
BytByteses
DescriptionDescription
ADDADD R/MR/M 11 Content of the Content of the Register Register or Memory or Memory is added to is added to the content of the content of Accumulator Accumulator and the and the result is stored in result is stored in AccumulatorAccumulator
SUBSUB R/MR/M 11 Content of the Content of the Register Register or Memory or Memory is subtracted is subtracted from the content of from the content of Accumulator Accumulator and the and the result is stored in result is stored in AccumulatorAccumulator
ADIADI 8 Bit 8 Bit DataData
22 8 Bit Data 8 Bit Data is added to is added to the content of the content of Accumulator Accumulator and the and the result is stored in result is stored in AccumulatorAccumulator
SUISUI 8 Bit 8 Bit DataData
22 8 Bit Data 8 Bit Data is subtracted is subtracted from the content of from the content of Accumulator Accumulator and the and the result is stored in result is stored in AccumulatorAccumulator
INRINR R/MR/M 11 The content of the The content of the specified specified Register or Register or MemoryMemory is is incrementedincremented by by 11
DCRDCR R/MR/M 11 The content of the The content of the specified specified Register or Register or MemoryMemory is is decrementeddecremented by by 11
118118
Computer Architecture
& Microprocessor
LoopsLoops
• Executes a set of instructions repeatedlyExecutes a set of instructions repeatedly• TypesTypes
Continuous LoopContinuous Loop Conditional LoopConditional Loop
Continuous LoopContinuous Loop• Uses unconditional jumpUses unconditional jump
Conditional LoopConditional Loop• Uses Conditional JumpUses Conditional Jump
119119
Computer Architecture
& Microprocessor
CounterCounter• Executes certain set of instructions a Executes certain set of instructions a
specified number of timesspecified number of times• Uses the concept of conditional loopUses the concept of conditional loop• Can be incremented or decrementedCan be incremented or decremented
120120
Computer Architecture
& Microprocessor
First ProgramFirst Program
Load a number to Register Load a number to Register BB and and display the output in display the output in Port1Port1
Steps:Steps:
1. Load register B with a Number1. Load register B with a Number
2. Send to Output to Port12. Send to Output to Port1
AlgorithmAlgorithm
Start
Input Number In Register
Output Number
Stop
121
CA & CA & µPµP
Unit IVUnit IV
122122
Computer Architecture
& Microprocessor
Setting up a CounterSetting up a Counter Executes certain set of instructions a specified number of Executes certain set of instructions a specified number of
timestimes
A Register is Loaded with a numberA Register is Loaded with a number
Using INR (Increment) or DCR (Decrement) the number is Using INR (Increment) or DCR (Decrement) the number is Incremented or DecrementedIncremented or Decremented
Uses the concept of conditional loopUses the concept of conditional loop
Time delay requiredTime delay required
If the register reaches the final count the loop is terminatedIf the register reaches the final count the loop is terminated
123123
Computer Architecture
& Microprocessor
Flowchart Flowchart Start
Initialize
Update
Is the Final Count
End
No
Yes
124124
Computer Architecture
& Microprocessor
Time DelayTime Delay
125125
Computer Architecture
& Microprocessor
T - StatesT - StatesOne Subdivision of the operation performed in one clock One Subdivision of the operation performed in one clock
periodperiod
Frequency & Time/Clock PeriodFrequency & Time/Clock PeriodFrequency in the Processing Speed of a ProcessorFrequency in the Processing Speed of a Processor
Time Period = (Frequency)Time Period = (Frequency)-1-1
Time PeriodTime Period = = 1 1
FrequencyFrequency
126126
Computer Architecture
& Microprocessor
Time DelayTime Delay
Uses the concept of counterUses the concept of counter No. of Counts depends on T-States.No. of Counts depends on T-States.
Calculation of Time for Execution:Calculation of Time for Execution: Clock Period = 1/frequencyClock Period = 1/frequency Time for Execution of Instruction = Time for Execution of Instruction =
No. of T-States X Clock PeriodNo. of T-States X Clock Period
127127
Computer Architecture
& Microprocessor
Simple Time Delay ProgramSimple Time Delay Program
MVI B, 77HMVI B, 77H -- 7 T-States7 T-States
Loop:Loop: DCR BDCR B -- 4 T-States4 T-States
JNZ JNZ LOOPLOOP -- 10/7 10/7 T-StatesT-States
HLTHLT -- 5 T-States5 T-States
128128
Computer Architecture
& Microprocessor
Time DelayTime Delay
Time Delay in executing the LoopTime Delay in executing the Loop
TTLL = (Time Period = (Time Period T T X X Loop T-States Loop T-States X X Equivalent Decimal Number Equivalent Decimal Number NN1010))
Total Time Delay in executing the LoopTotal Time Delay in executing the Loop
TTLALA = T = TLL – Time Adjustment – Time Adjustment
129129
Computer Architecture
& Microprocessor
Time Delay for the ProgramTime Delay for the Program
Let us Assume the Let us Assume the Frequency of the Frequency of the Processor is Processor is 2MHz2MHz
f = 2 MHzf = 2 MHz
T = 1/fT = 1/f
T = 1/2 MHzT = 1/2 MHz
T = 0.5 T = 0.5 µSec.µSec.
T-States Inside the LoopT-States Inside the Loop
DCR BDCR B -- 4 4
JNZ LOOPJNZ LOOP -- 1010
TotalTotal == 1414
T-States Outside the LoopT-States Outside the Loop
MVI B, FFHMVI B, FFH -- 7 7
HLTHLT -- 5 5
TotalTotal == 1212
Count
FFH = 25510
130130
Computer Architecture
& Microprocessor
Time Delay Inside the LoopTime Delay Inside the Loop
TTLL = T x T States x N = T x T States x N1010
TTLL = 0.5 = 0.5 µSec. x 14 x 255µSec. x 14 x 255
TTL L == 1785 1785 µSec.µSec.
TTL L = 1.785 mSec.= 1.785 mSec.
Total TimeTotal Time TTLALA = = 1.785 mSec. - (10-7) x 0.5 1.785 mSec. - (10-7) x 0.5 µSec.µSec.
TTLALA = 1.785 mSec. - 0.0015 mSec. = 1.785 mSec. - 0.0015 mSec.
TTLALA = = 1.7835 mSec.1.7835 mSec.
131131
Computer Architecture
& Microprocessor
Total Time Delay Total Time Delay
Time to Execute the instruction outside the loop Time to Execute the instruction outside the loop
TTDD = = + +
Time taken to execute the instruction inside the Time taken to execute the instruction inside the looploop
TTDD = T = TOO + T + TLALA
WhereWhere T TO O = T-States Outside the loop = T-States Outside the loop XX Time Time PeriodPeriod
132132
Computer Architecture
& Microprocessor
Total Time Delay Total Time Delay
TTOO = 12 x 0.5 = 12 x 0.5 µSec.µSec.
TTOO = .006 mSec. = .006 mSec.
TTDD = T = TOO + T + TLALA
TTDD = 0.006 mSec + 1.7835 mSec. = 0.006 mSec + 1.7835 mSec.
TTDD = 1.7895 mSec. = 1.7895 mSec.
TTDD ≈ 1.8 mSec. ≈ 1.8 mSec.
Total Time Required to execute the program is Total Time Required to execute the program is 1.8 milli Seconds 1.8 milli Seconds (Approx.)(Approx.)
133133
Computer Architecture
& Microprocessor
Note:Note:
Time Delay can be Varied by Time Delay can be Varied by changing the Count number changing the Count number FFH. FFH.
To Increase the time delay To Increase the time delay more the more the 1.8 mSec. 1.8 mSec. the user should use the the user should use the Additional Instruction or Additional Instruction or Register Pair.Register Pair.
134134
Computer Architecture
& Microprocessor
Time Delay Using Register PairTime Delay Using Register Pair
Program Program
LXI B, FFFFHLXI B, FFFFH -- 10 T-States10 T-States
Loop:Loop: DCX BDCX B -- 6 T-States6 T-States
MOV A, CMOV A, C -- 4 T-States4 T-States
ORA BORA B -- 4 T-States4 T-States
JNZ LoopJNZ Loop-- 10/7 T-States10/7 T-States
HLTHLT -- 5 T-States5 T-States
135135
Computer Architecture
& Microprocessor
Time DelayTime Delay
Let us Assume the Let us Assume the Frequency of the Frequency of the Processor is Processor is 2MHz2MHz
f = 2 MHzf = 2 MHz
T = 1/fT = 1/f
T = 1/2 MHzT = 1/2 MHz
T = 0.5 µSec.T = 0.5 µSec.
T-States Inside the LoopT-States Inside the Loop
DCX BDCX B -- 6 6
MOV A,CMOV A,C -- 4 4
ORA BORA B -- 4 4
JNZ LOOPJNZ LOOP -- 1010
TotalTotal == 2424
T-States Outside the T-States Outside the LoopLoop
LXI B, FFFFHLXI B, FFFFH -- 1010
HLTHLT -- 5 5
TotalTotal == 1515
Count
FFFFH = 6553510
136136
Computer Architecture
& Microprocessor
Time Delay in the Loop Time Delay in the Loop
TTLL = T x T States x N = T x T States x N1010
TTLL = 0.5 = 0.5 µSec. x 24 x 65535µSec. x 24 x 65535
TTL L == 786420 786420 µSec.µSec.
TTL L = 786.42 mSec.= 786.42 mSec.
Total TimeTotal Time TTLALA = = 786.42 mSec. - (10-7) x 0.5 786.42 mSec. - (10-7) x 0.5 µSec.µSec.
TTLALA = 786.42 mSec. - 0.0015 mSec. = 786.42 mSec. - 0.0015 mSec.
TTLALA = = 786.4185 mSec.786.4185 mSec.
137137
Computer Architecture
& Microprocessor
Total Time Delay Total Time Delay
TTOO = 15 x 0.5 = 15 x 0.5 µSec.µSec.
TTOO = .0075 mSec. = .0075 mSec.
TTDD = T = TOO + T + TLALA
TTDD = 0.0075 mSec + = 0.0075 mSec + 786.4185786.4185 mSec. mSec.
TTDD = = 786.426786.426 mSec. mSec.
TTDD ≈ 786.4 mSec. ≈ 786.4 mSec.
Total Time Required to execute the program is Total Time Required to execute the program is 786.4 milli 786.4 milli Seconds (Approx.)Seconds (Approx.)
138138
Computer Architecture
& Microprocessor
Flowchart Flowchart Start
Initialize Loop2
Update
Is the Final Count
End
Initialize Loop1
Update
Is the Final Count
No
No
Yes
Yes
139139
Computer Architecture
& MicroprocessorTime Delay Using Loop within a Time Delay Using Loop within a LoopLoop
Program Program
MVI B, FFHMVI B, FFH -- 10 T-States10 T-States
Loop2: Loop2: MVI C, FFHMVI C, FFH -- 10 T-States10 T-States
Loop1:Loop1: DCR CDCR C -- 6 T-States 6 T-StatesJNZ Loop1JNZ Loop1 -- 10/7 T-States10/7 T-States
DCR BDCR B -- 6 T-States 6 T-StatesJNZ Loop2JNZ Loop2 -- 10/7 T-States10/7 T-States
HLTHLT -- 5 T-States 5 T-States
L1 L2
140140
Computer Architecture
& Microprocessor
Time DelayTime Delay
Let us Assume the Let us Assume the Frequency of the Frequency of the Processor is Processor is 2MHz2MHz
f = 2 MHzf = 2 MHz
T = 1/fT = 1/f
T = 1/2 MHzT = 1/2 MHz
T = 0.5 µSec.T = 0.5 µSec.
T-States Inside the T-States Inside the Loop1Loop1
DCR CDCR C -- 4 4
JNZ Loop1JNZ Loop1 -- 1010
TotalTotal == 1414
T-States Inside the T-States Inside the Loop2Loop2
DCR CDCR C -- 4 4
JNZ Loop1JNZ Loop1 -- 7 7
DCR BDCR B -- 4 4
JNZ Loop2JNZ Loop2 -- 1010
TotalTotal == 2121
Count
Loop1 Count = FFH = 25510
Loop2 Count = FFH = 25510
T-States Outside the T-States Outside the LoopsLoops
MVI B, FFHMVI B, FFH -- 7 7
MVI C, FFHMVI C, FFH -- 7 7
HLTHLT -- 5 5
TotalTotal == 1919
141141
Computer Architecture
& Microprocessor
Time Delay in the Loop1Time Delay in the Loop1
TTL1L1 = T x T States x N = T x T States x N1010
TTL1L1 = 0.5 = 0.5 µSec. x 14 x 255µSec. x 14 x 255
TTL1 L1 == 1785 1785 µSec.µSec.
TTL1 L1 = 1.785 mSec.= 1.785 mSec.
Total TimeTotal Time TTLA1LA1 = = 1.785 mSec. - (10-7) x 0.5 1.785 mSec. - (10-7) x 0.5 µSec.µSec.
TTLA1LA1 = 1.785 mSec. - 0.0015 mSec. = 1.785 mSec. - 0.0015 mSec.
TTLA1LA1 = = 1.7835 mSec.1.7835 mSec.
142142
Computer Architecture
& Microprocessor
Time Delay in the Loop2Time Delay in the Loop2
TTL2L2 = (T = (TLA1LA1 + T-States X Time Period) X Count N + T-States X Time Period) X Count N1010
TTL2L2 = (1.7835 mSec. + 21 x 0.5 = (1.7835 mSec. + 21 x 0.5 µSec.) x 255µSec.) x 255
TTL2 L2 == 457470 457470 µSec.µSec.
TTL2 L2 = 457.47 mSec.= 457.47 mSec.
Total TimeTotal Time
TTLA2LA2 = = 457.47 mSec. - (10-7) x 0.5 457.47 mSec. - (10-7) x 0.5 µSec.µSec.
TTLA1LA1 = 457.47 mSec. - 0.0015 mSec. = 457.47 mSec. - 0.0015 mSec.
TTLA1LA1 = = 457.4685 mSec.457.4685 mSec.
143143
Computer Architecture
& Microprocessor
Total Time Delay Total Time Delay
TTOO = 19 x 0.5 = 19 x 0.5 µSec.µSec.
TTOO = .0095 mSec. = .0095 mSec.
TTDD = T = TOO + T + TLA2LA2
TTDD = 0.0095 mSec + = 0.0095 mSec + 457.4685457.4685 mSec. mSec.
TTDD = = 457.478457.478 mSec. mSec.
TTDD ≈ 457.5 mSec. ≈ 457.5 mSec.
Total Time Required to execute the program is Total Time Required to execute the program is 457.5 milli 457.5 milli Seconds (Approx.)Seconds (Approx.)
144144
Computer Architecture
& Microprocessor
Sample ProgramSample Program
Write a program to count continuously in hexadecimal Write a program to count continuously in hexadecimal from FFH to 00H in a system with a clock period of 0.5 from FFH to 00H in a system with a clock period of 0.5 µSec. Use Register D to setup one millisecond delay µSec. Use Register D to setup one millisecond delay between each count and display the count in one of the between each count and display the count in one of the Output PortsOutput Ports
Note:Note:
To Count from FFH the register to be initialized with To Count from FFH the register to be initialized with 0OH0OH Separate Time Delay Loop to be SetSeparate Time Delay Loop to be Set The Count to be Displayed in Output PortThe Count to be Displayed in Output Port
145145
Computer Architecture
& Microprocessor
ProgramProgram
MVI E, 00HMVI E, 00H -- 7 T-states7 T-states
Count:Count: DCR EDCR E -- 4 T-states4 T-states
MVI D, MVI D, Count No.Count No. -- 7 7 T-statesT-states
Delay:Delay: DCR DDCR D -- 4 T-states4 T-states
JNZ JNZ DelayDelay -- 10/7 T-states10/7 T-states
MOV A, BMOV A, B -- 4 T-states4 T-states
OUT OUT PortPort -- 10 T-states10 T-states
JMP CountJMP Count -- 10 T-states10 T-states
146146
Computer Architecture
& MicroprocessorTo Calculate Time Delay Count To Calculate Time Delay Count No.No.
T = 0.5 T = 0.5 µSec.µSec.
TTLL = (T-States x T) x Count No. = (T-States x T) x Count No.
TTLL = (14 x 0.5 µSec.) x Count No. = (14 x 0.5 µSec.) x Count No.
TTLL = 0.007 mSec. x Count No. = 0.007 mSec. x Count No.
TTLALA = (0.007 mSec. x Count) - 0.0015 mSec. = (0.007 mSec. x Count) - 0.0015 mSec.
TTOO = 35 x 0.5 µSec. = = 35 x 0.5 µSec. = 0.0175 mSec0.0175 mSec..
TTDD = (0.007 mSec. x Count) - 0.0015 mSec. + 0.0175 mSec. = (0.007 mSec. x Count) - 0.0015 mSec. + 0.0175 mSec.
1 mSec. = (0.007 mSec. x Count) + 1 mSec. = (0.007 mSec. x Count) + 0.016 mSec.0.016 mSec.
1 mSec. – 0.016 mSec.1 mSec. – 0.016 mSec.Count NoCount No. =. = = = 140.571 140.571 ≈ 141≈ 14110 10 ≈ 8CH≈ 8CH
0.007 mSec.0.007 mSec.
Count No. = 8CH, 8CH Count No. = 8CH, 8CH should be loaded into register should be loaded into register D D to set to set 1 1 millisecond millisecond delaydelay
147147
Computer Architecture
& Microprocessor
StackStack Set of Memory Locations in R/W memorySet of Memory Locations in R/W memory
Used to store binary information temporarily during the Used to store binary information temporarily during the execution of a programexecution of a program
Beginning of Stack is defined usingBeginning of Stack is defined using
LXI SP, 16 bit AddressLXI SP, 16 bit Address
Stack pointer is decremented by oneStack pointer is decremented by one
The byte stored to stack with the address specified in Stack The byte stored to stack with the address specified in Stack PointerPointer
The Storage & Retrieval on stack follows LIFO (Last in First Out) The Storage & Retrieval on stack follows LIFO (Last in First Out)
148148
Computer Architecture
& MicroprocessorStoring Register Pair Content to Storing Register Pair Content to StackStack Using Inst. Using Inst. PUSHPUSH the contents of a Register Pair can be copied to stack the contents of a Register Pair can be copied to stack
Using Inst. Using Inst. POPPOP the contents from the stack is copied to Register Pair the contents from the stack is copied to Register Pair
OP OP CodCod
ee
OpeOperanrandd
BytesBytes DescriptionDescription
PUSPUSHH
Rp.Rp. 11 Decrement the Decrement the Stack Pointer by Stack Pointer by one the content of one the content of higher order higher order (B, D, (B, D, H, A)H, A) is copied into is copied into stack then the stack then the Stack Pointer is Stack Pointer is again decremented again decremented the lower order the lower order (C, (C, E, L, Flags) E, L, Flags) is is copied into stackcopied into stack
POPPOP Rp.Rp. 11 Copy the content of Copy the content of the stack which is the stack which is pointer by stack pointer by stack pointer to lower pointer to lower order register order register (C, (C, E, L, Flags) E, L, Flags) and and increment the stack increment the stack pointer by one then pointer by one then Copy the content of Copy the content of the stack which is the stack which is pointer by stack pointer by stack pointer to higher pointer to higher order register order register (B, (B, D, H, A)D, H, A)
149149
Computer Architecture
& Microprocessor
Stack InstructionsStack Instructions
PUSH BPUSH B -- From Rp. From Rp. BC BC to Stackto Stack
PUSH DPUSH D -- From Rp. From Rp. DE DE to Stackto Stack
PUSH HPUSH H -- From Rp. From Rp. HL HL to Stackto Stack
PUSH PSWPUSH PSW -- From From Accumulator & Flags Accumulator & Flags to Stackto Stack
POP BPOP B -- From Stack to Rp. From Stack to Rp. BCBC
POP DPOP D -- From Stack to Rp. From Stack to Rp. DEDE
POP HPOP H -- From Stack to Rp. From Stack to Rp. HLHL
POP PSWPOP PSW -- From Stack to From Stack to Accumulator & FlagsAccumulator & Flags
Note: Note: PSW stands for PSW stands for Program Status WordProgram Status Word
150150
Computer Architecture
& Microprocessor
Example:Example:
Program:Program:
11 LXI SP, 2000HLXI SP, 2000H
22 LXI H, 4253HLXI H, 4253H
33 PUSH HPUSH H
44 NOPNOP
55 POP BPOP B
66 HLTHLT
151151
Computer Architecture
& MicroprocessorRegister Contents after Register Contents after executing first 2 Instructionsexecuting first 2 Instructions
XXXX
20002000
53534242
A
B
D
H
SP
Register Contents after Register Contents after executing PUSH Instructionsexecuting PUSH Instructions
XXXX
20002000
53534242
XX
4242
5353
MemoryMemory
A
B
D 1FFE
H 1FFF
SP 2000
152152
Computer Architecture
& MicroprocessorRegister Contents after Register Contents after executing POP Instructionsexecuting POP Instructions
53534242
20002000
53534242
XX
4242
5353
MemoryMemory
A Flags
B C
D E
H L
SP
153153
Computer Architecture
& Microprocessor
Program to Clear all Flags , Load 00H in the accumulator Program to Clear all Flags , Load 00H in the accumulator and demonstrate the zero flag is not affected by data and demonstrate the zero flag is not affected by data transfer instruction. Logically OR the accumulator with transfer instruction. Logically OR the accumulator with itself to set the zero flag, and display the flag at Port1 or itself to set the zero flag, and display the flag at Port1 or store all the flags on the stack.store all the flags on the stack.
LXI SP, 2000HLXI SP, 2000H -- Initialize Stack PointerInitialize Stack Pointer
MVI L, 00HMVI L, 00H
PUSH HPUSH H To Clear FlagsTo Clear Flags
POP PSWPOP PSW
MVI A, 00HMVI A, 00H -- Loading Accumulator with 00HLoading Accumulator with 00H
A Data Transfer InstructionA Data Transfer Instruction
PUSH PSWPUSH PSW
Getting Flag content to Reg. LGetting Flag content to Reg. L
POP HPOP H
154154
Computer Architecture
& Microprocessor
MOV A, LMOV A, LDisplay FlagsDisplay Flags
OUT Port1OUT Port1
ORA AORA A -- Reset CY & ACReset CY & AC
PUSH PSWPUSH PSW Getting Flag content to Reg. LGetting Flag content to Reg. L
POP HPOP H
MOV A, LMOV A, L
ANI 40HANI 40H Masking all flags except Z & DisplayMasking all flags except Z & Display
OUT Port1OUT Port1
HLTHLT -- End of the ProgramEnd of the Program
155155
Computer Architecture
& Microprocessor
SubroutineSubroutine It is group of Instructions written separately from the main program to perform a It is group of Instructions written separately from the main program to perform a
function no. of times in the main program.function no. of times in the main program. If a Time Delay is required for no. of times in a main program, to avoid repetition If a Time Delay is required for no. of times in a main program, to avoid repetition
of same delay instruction, Subroutine is usedof same delay instruction, Subroutine is used
InstructionInstruction
OP OP CodeCode
OperOperandand
BytesBytes DescriptionDescription
CALLCALL 16 16 bit bit addraddressess
33 The Program The Program Sequence is Sequence is transferred to the transferred to the specified 16 bit specified 16 bit address address
RETRET NoneNone 11 The Program The Program Sequence is Sequence is transferred from transferred from subroutine to subroutine to calling program.calling program.
156156
Computer Architecture
& Microprocessor
CALL & RETCALL & RET
Call Inst.Call Inst.• Saves the contents of Program Counter on the stackSaves the contents of Program Counter on the stack• Jumps unconditionally to the memory location Jumps unconditionally to the memory location
specified by 16 bit address (Note: Conditional Call specified by 16 bit address (Note: Conditional Call Statements are also there)Statements are also there)
RET inst.RET inst.• Copies the content in the top two location of the Copies the content in the top two location of the
stackstack• Unconditional Return from Subroutine (Note: Unconditional Return from Subroutine (Note:
Conditional Return Statements are also there)Conditional Return Statements are also there)
157157
Computer Architecture
& Microprocessor
ExampleExample
Mem. Mem. Add.Add.
InstrucInstructiontion
DescriptionDescription
20002000HH
LXI SP, LXI SP, 4000H4000H
Initialize the stack pointer Initialize the stack pointer with 2400Hwith 2400H
20042004HH
CALL CALL 3000H3000H
Calling the subroutine at Calling the subroutine at 3000H3000H
20072007HH
Inst. Inst. Other InstructionsOther Instructions
20082008HH
HLTHLT End of Main ProgramEnd of Main Program
30003000HH
Inst.Inst. Instructions of SubroutineInstructions of Subroutine
30013001HH
Inst.Inst. Instructions of SubroutineInstructions of Subroutine
30023002HH
RETRET End of SubroutineEnd of Subroutine
158158
Computer Architecture
& Microprocessor
Flow of SubroutineFlow of Subroutine
Main ProgramMain Program2000H2000H SubroutineSubroutine
……
2004H2004H 3000H 3000H StartStart
2005H2005H 3001H 3001H
2006H2006H 3002H 3002H EndEnd
…… … …
…… … …
……
159159
Computer Architecture
& MicroprocessorData Transfer During CALL Data Transfer During CALL InstructionInstruction
Mem. Mem. Add.Add.
Code Code (H)(H)
20042004HH
CDCD
20052005HH
0000
20062006HH
3030
160160
Computer Architecture
& MicroprocessorPC, Stack & SP during CALL PC, Stack & SP during CALL Inst.Inst.
20200404
20200505
20200606
20200707
0077
2200
XXXX
CALL 40400000
3F3FFFFF
3F3FFEFE
Program Counter
Stack Pointer Register
3FFE
3FFF
4000
STACK
161161
Computer Architecture
& MicroprocessorData Transfer During CALL Data Transfer During CALL InstructionInstruction
MachiMachine ne
CycleCycless
Stack Stack PointPoint
erer
3FFE3FFE
AddrAddress ess BusBus
(AB)(AB)
ProgrProgram am
CountCounterer
Data Data BusBus
(DB)(DB)
InterInternal nal
RegisRegistersters
(W) (W) (Z)(Z)
MM11
OpcodOpcode e
FetchFetch
3FFE3FFE 30023002 30033003 C9C9
OpcodOpcodee
--
MM22
OpcodOpcode e
FetchFetch
3FFF3FFF 3FFE3FFE 0707
(Stack(Stack))
0707
MM33
OpcodOpcode e
FetchFetch
40004000 3FFF3FFF 2020
(Stack (Stack – I)– I)
2020
MM11
OpcodOpcode e
FetchFetch
20072007
(W) (W) (Z)(Z)
20 0720 07
(W) (W) (Z)(Z)
162162
Computer Architecture
& Microprocessor
Traffic Signal ControllerTraffic Signal ControllerProgram to provide given on/off timer to three traffic lights Program to provide given on/off timer to three traffic lights (Green, Yellow, and Red) and two pedestrian signs (WALK (Green, Yellow, and Red) and two pedestrian signs (WALK and DON’T WALK). The signal lights and signs are turned and DON’T WALK). The signal lights and signs are turned on/off by the data bits of an output port as shown below:on/off by the data bits of an output port as shown below:
Lights Lights Data Bits Data Bits On TimeOn Time
1. Green1. Green D0D0 15 seconds15 seconds
2. Yellow2. Yellow D2D2 5 seconds 5 seconds
3. Red3. Red D4D4 20 seconds20 seconds
4. WALK4. WALK D6D6 15 seconds15 seconds
5. DON’T WALK5. DON’T WALK D7D7 25 seconds25 seconds
The traffic and pedestrian flow are in the same direction; the The traffic and pedestrian flow are in the same direction; the pedestrian should cross the road when the Green light is on. pedestrian should cross the road when the Green light is on.
163163
Computer Architecture
& Microprocessor
The problem is primarily concerned with providing various time delays for a complete sequence of 40 seconds.
The on/off times for the traffic signals and pedestrian signs are as follows:
164164
Computer Architecture
& Microprocessor
The Green light and the WALK sign can be turned The Green light and the WALK sign can be turned on by sending data byte 41H to the output port. on by sending data byte 41H to the output port.
The 15-second delay can be provided by using a The 15-second delay can be provided by using a 1-second subroutine and a counter with a count 1-second subroutine and a counter with a count of 1510. of 1510.
Similarly, the next two bytes, 84H and 90H, will Similarly, the next two bytes, 84H and 90H, will turn on/off the appropriate lights/signs as shown turn on/off the appropriate lights/signs as shown in the flowchart. in the flowchart.
The necessary time delays are provided by The necessary time delays are provided by changing the values of the count in the counter. changing the values of the count in the counter.
165165
Computer Architecture
& MicroprocessorMain ProgramMain ProgramLXI SP, XX99 LXI SP, XX99 -- Initialize Stack Pointer with XX99HInitialize Stack Pointer with XX99H
START:START: MVI A, 41H MVI A, 41H -- Loading Accumulator with Pattern for Loading Accumulator with Pattern for Green & WalkGreen & Walk
OUT OUT PORT1PORT1 -- Turn on corresponding lightsTurn on corresponding lights
MVI B, 0FH MVI B, 0FH -- Reg. B is used to count 15 secondsReg. B is used to count 15 seconds
CALL CALL DELAY DELAY -- Call subroutine of one second delayCall subroutine of one second delay
MVI A, 90HMVI A, 90H -- Loading Accumulator with Pattern Loading Accumulator with Pattern
OUT OUT PORT1PORT1 -- Turn on corresponding lightsTurn on corresponding lights
MVI B, 05 MVI B, 05 -- Reg. B is used to count 5 secondsReg. B is used to count 5 seconds
CALL CALL DELAYDELAY -- Call subroutine of one second delayCall subroutine of one second delay
MVI A, 90H MVI A, 90H -- Loading Accumulator with PatternLoading Accumulator with Pattern
OUT OUT PORT1PORT1 - - Turn on corresponding lightsTurn on corresponding lights
MVI B, 14HMVI B, 14H -- Reg. B is used to count 20 secondsReg. B is used to count 20 seconds
CALL CALL DELAYDELAY - - Call subroutine of one second delayCall subroutine of one second delay
JMP JMP START START -- Go to START to repeat the SequenceGo to START to repeat the Sequence
166166
Computer Architecture
& MicroprocessorSubroutineSubroutineDelay:Delay: PUSH DPUSH D Save the contents of DE & AccumulatorSave the contents of DE & Accumulator
PUSH PSWPUSH PSW
Sec:Sec: LXI D, LXI D, COUNT No.COUNT No. -- Load Rp. DE with Count No.Load Rp. DE with Count No.
Loop:Loop: DCX DDCX D -- Decrement Rp. DE by oneDecrement Rp. DE by one
MOV A, DMOV A, D Check Rp. DE is ZeroCheck Rp. DE is Zero
ORA EORA E
JNZ JNZ LoopLoop -- Jump to Loop if Zero Flag is not SetJump to Loop if Zero Flag is not Set
DCR BDCR B -- Decrement Reg. BDecrement Reg. B
JNZ JNZ SecSec -- Jump to Sec if Zero Flag is not SetJump to Sec if Zero Flag is not Set
POP PSWPOP PSW
POP DPOP D Retrieve contents of saved RegistersRetrieve contents of saved Registers
RETRET -- Returning to Main ProgramReturning to Main Program
167167
Computer Architecture
& Microprocessor
BCD – Binary Coded DecimalBCD – Binary Coded Decimal
868610 10 = (8 x 10) + 2= (8 x 10) + 2
Converting a 2-digit BCD number into its binary Converting a 2-digit BCD number into its binary equivalent requires the following steps:equivalent requires the following steps:
• Separate an 8-bit packed BCD number into two 4-bit Separate an 8-bit packed BCD number into two 4-bit unpacked BCD digits: BCD1 and BCD2.unpacked BCD digits: BCD1 and BCD2.
• Convert each digit into its binary value according to its Convert each digit into its binary value according to its position.position.
• Add both binary numbers to obtain the binary equivalent of Add both binary numbers to obtain the binary equivalent of the BCD number.the BCD number.
168168
Computer Architecture
& Microprocessor
ExampleExample
Convert (86)BCD into its binary equivalent Convert (86)BCD into its binary equivalent
Solution:Solution: 86861010 = 1000 0110 BCD = 1000 0110 BCD
0111 0010 0111 0010 • 00000110 Unpacked BCD100000110 Unpacked BCD1• 00001000 Unpacked BCD200001000 Unpacked BCD2
Multiply BCD2 by 10 (8 x 10)Multiply BCD2 by 10 (8 x 10)
Add BCD1 to the answer in Step 2.Add BCD1 to the answer in Step 2.
169169
Computer Architecture
& Microprocessor
2 Digit BCD to Binary 2 Digit BCD to Binary ConversionConversion
A BCD number between 0 and 99 is stored in a R/W memory A BCD number between 0 and 99 is stored in a R/W memory location called the Input Buffer. Write a main program and a location called the Input Buffer. Write a main program and a conversion subroutine (BCDBIN) to convert the BCD number into conversion subroutine (BCDBIN) to convert the BCD number into its equivalent binary number. Store the result in a memory its equivalent binary number. Store the result in a memory location defined as the Output Buffer.location defined as the Output Buffer.
LXI SP, LXI SP, “STACK”“STACK” -- Initialize stackInitialize stack
LXI H, LXI H, “INBUF”“INBUF” -- Initialize Input LocationInitialize Input Location
LXI B, LXI B, “OUTBUF”“OUTBUF” -- Initialize Output LocationInitialize Output Location
MOV A, M MOV A, M -- Input of BCD No.Input of BCD No.
CALL CALL BCDBINBCDBIN -- Calling SubroutineCalling Subroutine
STAX B STAX B -- Storing Binary No. to Output Buf.Storing Binary No. to Output Buf.
HLT HLT -- End of the ProgramEnd of the Program
Main ProgramMain Program
170170
Computer Architecture
& MicroprocessorSubroutineSubroutineBCDBIN; BCD to BinaryBCDBIN; BCD to Binary
; I/P: packed BCD in Acc.; I/P: packed BCD in Acc.
; O/P: Binary in Acc.; O/P: Binary in Acc.
PUSH BPUSH B -- Save Rp. Save Rp.
MOV B, AMOV B, A -- Copies Acc. Contents to Reg. BCopies Acc. Contents to Reg. B
ANI 0FHANI 0FH -- ANDing (A) with 0FH to mask MSBANDing (A) with 0FH to mask MSB
MOV C, AMOV C, A -- Copies Acc. Contents to Reg. CCopies Acc. Contents to Reg. C
MOV A, BMOV A, B -- Copies Reg. B contents to Acc.Copies Reg. B contents to Acc.
ANI F0HANI F0H -- ANDing (A) with F0H to mask LSBANDing (A) with F0H to mask LSB
RRCRRC
RRCRRC Making MSB as LSBMaking MSB as LSB
RRCRRC
RRCRRC
MOV D, AMOV D, A -- Copies Acc. Contents to Reg. DCopies Acc. Contents to Reg. D
XRA AXRA A -- Clearing Acc. & FlagsClearing Acc. & Flags Cont.
171171
Computer Architecture
& Microprocessor
MVI E, 0AHMVI E, 0AH -- Load Reg. E with 0AH = 10Load Reg. E with 0AH = 101010
Sum:Sum: ADD EADD E -- Add (E) to (A)Add (E) to (A)
DCR DDCR D -- Decrement (D) by oneDecrement (D) by one
JNZ JNZ SumSum -- Jump to location Sum in Zero flag is resetJump to location Sum in Zero flag is reset
ADD CADD C -- Add (C) to (A)Add (C) to (A)
POP BPOP B -- Retrieve (BC)Retrieve (BC)
RETRET -- Returning to Main ProgramReturning to Main Program
Cont.
172172
Computer Architecture
& MicroprocessorBinary to BCDBinary to BCDA binary number is stored in memory location BINBYT. Convert the A binary number is stored in memory location BINBYT. Convert the number into BCD, and store each BCD as unpacked BCD digits in the number into BCD, and store each BCD as unpacked BCD digits in the Output Buffer. To perform this task, write a main program and two Output Buffer. To perform this task, write a main program and two subroutines: one to supply the powers of ten, and the other to subroutines: one to supply the powers of ten, and the other to perform the conversion. perform the conversion.
Main ProgramMain Program
STARTSTART:LXI SP, STACK:LXI SP, STACK -- Initialize stack pointerInitialize stack pointer
LXI H, BINBYTLXI H, BINBYT -- Point HL index where binary number is Point HL index where binary number is storedstored
MOV A, MMOV A, M -- Transfer byteTransfer byte
CALL CALL PWRTENPWRTEN -- Call subroutine to load powers of 10Call subroutine to load powers of 10
HLTHLT -- End of the ProgramEnd of the Program
173173
Computer Architecture
& MicroprocessorSubroutine PWRTENSubroutine PWRTENPWRTENPWRTEN; Loads the powers of 10 in register B and calls the ; Loads the powers of 10 in register B and calls the
binary to BCDbinary to BCD
;I/P: Binary number in the accumulator;I/P: Binary number in the accumulator
;O/P: Powers of ten and store BCD;O/P: Powers of ten and store BCD11 in the first Output- in the first Output-BufferBuffer
;Calls BINBCD routine and modifies register B;Calls BINBCD routine and modifies register B
::LXI H, LXI H, OUTBUFOUTBUF - - Point HL index to Output-Buffer Point HL index to Output-Buffer memorymemory
MVI B, 64HMVI B, 64H - - Load 100 in register BLoad 100 in register B
CALL CALL BINBCDBINBCD - - Call conversionCall conversion
MVI B, 0AHMVI B, 0AH - - Load 10 in register BLoad 10 in register B
CALL CALL BINBCDBINBCD - - Calls BINBCD subroutineCalls BINBCD subroutine
MOV M, AMOV M, A - - Store BCDStore BCD11
RETRET - - Returning to Main ProgramReturning to Main Program
174174
Computer Architecture
& MicroprocessorSubroutine BINBCDSubroutine BINBCDBINBCDBINBCD ;Converts a binary number into BCD and stores BCD2 ;Converts a binary number into BCD and stores BCD2
and and
;BCD3 in the Out put Buffer.;BCD3 in the Out put Buffer.
;I/P: Binary number in accumulator and powers of 10 in B;I/P: Binary number in accumulator and powers of 10 in B
;O/P: BCD2 and BCD3 in Output Buffer;O/P: BCD2 and BCD3 in Output Buffer
;Modifies accumulator contents;Modifies accumulator contents
:MVI M, FFH -:MVI M, FFH - Load buffer with (0 -1)Load buffer with (0 -1)
NB:NB: INR MINR M - - Clear buffer and increment for each Clear buffer and increment for each subtractionsubtraction SUB BSUB B - - Subtract power of 10 from Subtract power of 10 from binary numberbinary number
JNC JNC NBNB - - Is number > power of 10? If yes, add 1 Is number > power of 10? If yes, add 1 to bufferto buffer
ADD BADD B - - If no, add power of 10 to get remainderIf no, add power of 10 to get remainder
INX HINX H - - Go to next buffer locationGo to next buffer location
RETRET - - Returning to Subroutine PWRTENReturning to Subroutine PWRTEN
175175
Computer Architecture
& MicroprocessorBCD to 7 Segment DisplayBCD to 7 Segment DisplayWrite a main program and two subroutines, called UNPAK and Write a main program and two subroutines, called UNPAK and LEDCOD, to unpack the BCD numbers and select an appropriate LEDCOD, to unpack the BCD numbers and select an appropriate seven-segment code for each digit. The codes should be stored in seven-segment code for each digit. The codes should be stored in the Output-Buffer memory. the Output-Buffer memory.
Main ProgramMain Program
LXI SP, STACKLXI SP, STACK -- Initialize stack pointerInitialize stack pointer
LXI H, XX50HLXI H, XX50H -- Point HL index where BCD digits are storedPoint HL index where BCD digits are stored
MVI D, 03HMVI D, 03H -- Number of digits to be converted is placed in DNumber of digits to be converted is placed in D
CALL CALL UNPAKUNPAK-- Call subroutine to unpack BCD numbersCall subroutine to unpack BCD numbers
HLTHLT -- End of ProgramEnd of Program
176176
Computer Architecture
& MicroprocessorSubroutine UNPACKSubroutine UNPACKUNPAK;UNPAK;This subroutine unpacks the BCD number into two single This subroutine unpacks the BCD number into two single
digits.digits.
;I/P: Starting memory address of the packed BCD numbers in HL ;I/P: Starting memory address of the packed BCD numbers in HL ;registers: Number of BCDs to be converted in register D;registers: Number of BCDs to be converted in register D
;O/P: Unpacked BCD into acc. and Output Buffer address in BC;O/P: Unpacked BCD into acc. and Output Buffer address in BC
;Calls subroutine LEDCOD;Calls subroutine LEDCOD
LXI B, BUFFERLXI B, BUFFER -- Point BC index to the buffer memoryPoint BC index to the buffer memory
NBCDNBCD:: MOV A, MMOV A, M -- Get packed BCD numberGet packed BCD number
ANI F0HANI F0H -- Masked BCD1Masked BCD1
RRCRRC Rotate four times to place BCD2 asRotate four times to place BCD2 as
RRCRRC unpacked single digit BCDunpacked single digit BCD
RRCRRC
RRCRRC
177177
Computer Architecture
& MicroprocessorSubroutine UNPACKSubroutine UNPACK
CALL LEDCODCALL LEDCOD -- Find seven-segment codeFind seven-segment code
INX BINX B -- Point to next buffer locationPoint to next buffer location
MOV A, MMOV A, M -- Get BCD number againGet BCD number again
ANI 0FHANI 0FH -- Separate BCD1Separate BCD1
CALL LEDCODCALL LEDCOD --
INX BINX B --
INX HINX H -- Point to next BCDPoint to next BCD
DCR DDCR D -- Conversion complete, reduce BCD Conversion complete, reduce BCD countcount
JNZ JNZ NBCDNBCD -- If all BCDs are not yet converted, If all BCDs are not yet converted, go back go back
to convert nextto convert next
RETRET -- Return to Main ProgramReturn to Main Program
178178
Computer Architecture
& MicroprocessorSubroutine LEDCODSubroutine LEDCOD
LEDCODLEDCOD;This subroutine converts an unpacked BCD into its ;This subroutine converts an unpacked BCD into its seven-segment seven-segment
; LED code; LED code
;I/P: An unpacked BCD in accumulator ;I/P: An unpacked BCD in accumulator
;Memory address of the buffer in BC register;Memory address of the buffer in BC register
;O/P: Stores seven-segment code in the output buffer;O/P: Stores seven-segment code in the output buffer
: PUSH H : PUSH H -- Save HL contents of the callerSave HL contents of the caller
LXI H, CODELXI H, CODE -- Point index to beginning of 7-segment codePoint index to beginning of 7-segment code
ADD LADD L -- Add BCD digit to starting address of codeAdd BCD digit to starting address of code
MOV L, AMOV L, A -- Point HL to appropriate codePoint HL to appropriate code
MOV A, MMOV A, M -- Get seven-segment codeGet seven-segment code
STAX BSTAX B -- Store code in bufferStore code in buffer
POP HPOP H -- Retrieve (HL) Rp.Retrieve (HL) Rp.
RETRET -- Return to Subroutine UNPACKReturn to Subroutine UNPACK
179179
Computer Architecture
& MicroprocessorBinary to ASCIIBinary to ASCIIWrite a program to Transfer the byte to the accumulator, Separate Write a program to Transfer the byte to the accumulator, Separate the two nibbles (as 09 and 0F). Call the subroutine to convert each the two nibbles (as 09 and 0F). Call the subroutine to convert each nibble into ASCII Hex code and Store the codes in memory nibble into ASCII Hex code and Store the codes in memory locations XX60H AND XX61H. Write a subroutine to convert a locations XX60H AND XX61H. Write a subroutine to convert a binary digit (0 to F) into ASCII Hex code.. An 8-bit binary number binary digit (0 to F) into ASCII Hex code.. An 8-bit binary number (e.g., 9FH) is stored in memory location XX50H.(e.g., 9FH) is stored in memory location XX50H.
Main ProgramMain ProgramLXI SP, STACKLXI SP, STACK -- Initialize stack pointerInitialize stack pointer
LXI H, XX50HLXI H, XX50H-- Point index where binary number is storedPoint index where binary number is stored
LXI D, XX60HLXI D, XX60H-- Point index where ASCII code is to be storedPoint index where ASCII code is to be stored
MOV A, MMOV A, M -- Transfer byteTransfer byte
MOV B, AMOV B, A -- Save byteSave byte
RRCRRC Shift high-order nibble to the position of low-Shift high-order nibble to the position of low-
RRC RRC order nibbleorder nibble
RRCRRC
RRCRRC
180180
Computer Architecture
& MicroprocessorBinary to ASCIIBinary to ASCIIMain Program – Cont.Main Program – Cont.
CALL ASCIICALL ASCII -- Call conversion routineCall conversion routine
STAX DSTAX D -- Store first ASCII Hex in Store first ASCII Hex in XX60HXX60H
INX DINX D -- point to next memory point to next memory location, get ready to location, get ready to
store next bytestore next byte
MOV A, BMOV A, B -- Get number again for Get number again for second digitsecond digit
CALL ASCIICALL ASCII
STAX DSTAX D
HLTHLT
181181
Computer Architecture
& MicroprocessorBinary to ASCIIBinary to ASCIISubroutine – ASCIISubroutine – ASCII
ASCIIASCII ; Converts a binary digit between 0 and F to ; Converts a binary digit between 0 and F to ASCII Hex codeASCII Hex code
;Input: Single binary number 0 to F in the ;Input: Single binary number 0 to F in the accumulatoraccumulator
;Output: ASCII Hex code in the accumulator;Output: ASCII Hex code in the accumulator
:ANI 0FH:ANI 0FH -- Mask high-order nibbleMask high-order nibble
CIP 0AHCIP 0AH -- Is digit less than 1010?Is digit less than 1010?
JC JC CODECODE -- If digit is less than 1010, go to CODE If digit is less than 1010, go to CODE to add to add 30H30H
ADI 07HADI 07H -- Add 7H to obtain code for digits from Add 7H to obtain code for digits from A to FA to F
CODE:CODE: ADI 30HADI 30H -- Add base number 30HAdd base number 30H
RET RET -- Return to Main ProgramReturn to Main Program
182182
Computer Architecture
& MicroprocessorASCII to BinaryASCII to BinaryWrite a subroutine to convert an ASCII Hex number into its Write a subroutine to convert an ASCII Hex number into its binary equivalent. A calling program places the ASCII number binary equivalent. A calling program places the ASCII number in the accumulator, and the subroutine should pass the in the accumulator, and the subroutine should pass the conversion back to the accumulator.conversion back to the accumulator.
SubroutineSubroutine
ASCBINASCBIN;This subroutine converts an ASCII Hex number into its ;This subroutine converts an ASCII Hex number into its binarybinary
;Input: ASCII Hex number in the accumulator;Input: ASCII Hex number in the accumulator
;Output: Binary equivalent in the accumulator;Output: Binary equivalent in the accumulator
:SUI 30H:SUI 30H -- Subtract 0 bias from the numberSubtract 0 bias from the number
CPI 0AHCPI 0AH -- Check whether number is between 0 and 9Check whether number is between 0 and 9
RCRC -- If yes, return to main programIf yes, return to main program
SUI 07HSUI 07H -- If not, sub. 7 to find number between A If not, sub. 7 to find number between A & F& F
RETRET -- Return to Main ProgramReturn to Main Program
183183
Computer Architecture
& MicroprocessorBCD MultiplicationBCD MultiplicationA multiplicand is stored in memory location XX50H and a A multiplicand is stored in memory location XX50H and a multiplier is stored in location XX51H. Write a main program multiplier is stored in location XX51H. Write a main program to transfer the two numbers from memory locations to the HL to transfer the two numbers from memory locations to the HL registers and store the product in the Output Buffer at XX90H. registers and store the product in the Output Buffer at XX90H. Write a subroutine to Multiply two unsigned numbers placed in Write a subroutine to Multiply two unsigned numbers placed in registers H and L and Return the result into the HL pair.registers H and L and Return the result into the HL pair.
Main ProgramMain Program
LXI SP, STACKLXI SP, STACK
LHLD XX50HLHLD XX50H-- Place contents of XX50 in L register and Place contents of XX50 in L register and
contents of XX51 in H registercontents of XX51 in H register
XCHGXCHG -- Place multiplier in D and multiplicand in Place multiplier in D and multiplicand in EE
CALL MLTPLYCALL MLTPLY -- Multiply the two numbersMultiply the two numbers
SHLD XX90HSHLD XX90H -- Store the product in locations XX90 and Store the product in locations XX90 and 91H91H
HLTHLT -- End of the ProgramEnd of the Program
184184
Computer Architecture
& MicroprocessorBCD MultiplicationBCD MultiplicationSubroutine - MLTPLYSubroutine - MLTPLY
MLTPLY:MOV A, DMLTPLY:MOV A, D -- Transfer multiplier to accumulatorTransfer multiplier to accumulator
MVI D, 00HMVI D, 00H -- Clear D to use in DAD instructionClear D to use in DAD instruction
LXI H, 0000HLXI H, 0000H -- Clear HLClear HL
MVI B, 08HMVI B, 08H -- Set up register B to count eight rotationsSet up register B to count eight rotations
NXTBIT:RARNXTBIT:RAR -- Check if multiplier bit is 1Check if multiplier bit is 1
JNC NOADDJNC NOADD -- If not, skip adding multiplicandIf not, skip adding multiplicand
DAD DDAD D -- If multiplier is 1, add multiplicand to HL If multiplier is 1, add multiplicand to HL and and place partial result in HLplace partial result in HL
NOADD:XCHGNOADD:XCHG -- Place multiplicand in HLPlace multiplicand in HL
DAD HDAD H -- And shift leftAnd shift left
XCHGXCHG -- Retrieve shifted multiplicationRetrieve shifted multiplication
DCR BDCR B -- One operation is complete, decrement One operation is complete, decrement countercounter
JNZ NXTBITJNZ NXTBIT -- Go back to next bitGo back to next bit
RETRET -- Return To Main ProgramReturn To Main Program
185185
Computer Architecture
& Microprocessor
Interfacing Peripherals Interfacing Peripherals
Primary Function of MPU is to accept and send data Primary Function of MPU is to accept and send data from I/P & to O/P Devicesfrom I/P & to O/P Devices
These I/O & O/P Devices are called peripherals or I/OsThese I/O & O/P Devices are called peripherals or I/Os
Interfacing is to enable the MPU to communicate with Interfacing is to enable the MPU to communicate with the peripherals.the peripherals.
186186
Computer Architecture
& Microprocessor
Classification of InterfacingClassification of Interfacing CommunicationCommunication
• Synchronous Synchronous – Both transmitter & Receiver aer – Both transmitter & Receiver aer synchronized by same clock pulsesynchronized by same clock pulse
• Asynchronous Asynchronous – Both of Irregular Intervals– Both of Irregular Intervals
Transfer of DataTransfer of Data• Parallel – Parallel – Entire word is transmitted at a timeEntire word is transmitted at a time• Serial – Serial – One bit at a time over single lineOne bit at a time over single line
I/O TypesI/O Types• Peripheral I/O – Peripheral I/O – Identified with 8 bit addressIdentified with 8 bit address• Memory mapped I/O – Memory mapped I/O – Identified with 16 bit addressIdentified with 16 bit address
187187
Computer Architecture
& Microprocessor
InterruptInterrupt A computer input that temporarily suspends the normal A computer input that temporarily suspends the normal
sequence of operations and transfer control to a special sequence of operations and transfer control to a special routine.routine.
Interrupt Process is controlled by Interrupt Enable flip-Interrupt Process is controlled by Interrupt Enable flip-flop, which can be set or reset by using software flop, which can be set or reset by using software Instruction.Instruction.
INTR (pin 10) goes high the Microprocessor is interrupted, INTR (pin 10) goes high the Microprocessor is interrupted, which is maskable & can be disabledwhich is maskable & can be disabled
Microprocessor also has additional vectored interrupt Microprocessor also has additional vectored interrupt signals.signals.
188188
Computer Architecture
& Microprocessor
Vectored InterruptVectored Interrupt
MaskableMaskable• RST 7.5RST 7.5 -- 003CH003CH• RST 6.5RST 6.5 -- 0034H0034H• RST 5.5RST 5.5 -- 002CH002CH
Non-maskableNon-maskable• TRAPTRAP -- 0024H0024H
189189
Computer Architecture
& MicroprocessorInterrupt InstructionInterrupt Instruction
OP OP CodeCode
OperOperandand
BytByteses
DescriptionDescription
EIEI NoneNone 11 The Interrupt Enable flip-The Interrupt Enable flip-flop is set and all the flop is set and all the interrupts are enabledinterrupts are enabled
DIDI NoneNone 11 The Interrupt Enable flip-The Interrupt Enable flip-flop is reset and all the flop is reset and all the interrupts except TRAP interrupts except TRAP are disabledare disabled
MneMnemonimoni
cscs
Hex Hex CodCod
ee
Call Call LocatiLocati
onon
RST RST 00
C7C7 00000000HH
RST RST 11
CFCF 00080008HH
RST RST 22
D7D7 00100010HH
RST RST 33
DFDF 00180018HH
RST RST 44
E7E7 00200020HH
RST RST 55
EFEF 00280028HH
RST RST 66
F7F7 00300030HH
RST RST 77
FFFF 00380038HH
RST InstructionRST Instruction
190190
Computer Architecture
& MicroprocessorReal Time Example to InterruptReal Time Example to Interrupt Interrupt Process is to compare it to a telephone line with a Interrupt Process is to compare it to a telephone line with a
blinking light instead of ring when you are reading a book.blinking light instead of ring when you are reading a book.
SteStep p 1:1:
The Telephone The Telephone System should be System should be enabled enabled
The interrupt The interrupt process should be process should be enabled by writing enabled by writing the instruction EI the instruction EI
SteStep p 2:2:
Have glance at the Have glance at the light at certain light at certain intervals to check intervals to check whether someone whether someone is calling is calling
When the When the microprocessor is microprocessor is executing a executing a program, it checks program, it checks the INTR line the INTR line during the during the execution of each execution of each instruction. instruction.
SteStep p 3:3:
If you see a If you see a blinking light, you blinking light, you should pick up the should pick up the receiver, say hello, receiver, say hello, and wait for a and wait for a response. Once response. Once you pick up the you pick up the phone, the line is phone, the line is busy, and no more busy, and no more calls can be calls can be received until you received until you replace the replace the receiver. receiver.
If the line INTR is If the line INTR is high and the high and the interrupt is interrupt is enabled, the enabled, the microprocessor microprocessor completes the completes the current current instruction, instruction, disables the disables the Interrupt Enable Interrupt Enable flip-flop and sends flip-flop and sends a signal called a signal called INTA – Interrupt INTA – Interrupt Acknowledge Acknowledge (active low). The (active low). The processor cannot processor cannot accept any accept any interrupt requests interrupt requests until the interrupt until the interrupt flip-flop is enabled flip-flop is enabled again. again.
191191
Computer Architecture
& Microprocessor
SteStep p 4:4:
Assuming that the Assuming that the caller is you caller is you roommate, the roommate, the request may be: It request may be: It is going to rain is going to rain today. Will you today. Will you please shut all the please shut all the windows in my windows in my room? room?
The signal INTA is The signal INTA is used to insert an used to insert an instruction, instruction, preferably, a preferably, a restart (RST) restart (RST) instruction, instruction, through additional through additional hardware. The RST hardware. The RST instruction is a 1-instruction is a 1-byte call byte call instruction that instruction that transfers the transfers the program control to program control to a specific memory a specific memory location on page location on page 00H and restarts 00H and restarts the execution at the execution at that memory that memory location after location after executing Next executing Next StepStep
SteStep p 5:5:
You insert a You insert a bookmark on the bookmark on the page you are page you are reading reading
It saves the It saves the memory address of memory address of the next the next instruction on the instruction on the stack and the stack and the program is program is transferred to the transferred to the CALL location. CALL location.
SteStep p 6:6:
You replace the You replace the receiver on the receiver on the hook hook
Assuming that the Assuming that the task to be task to be performed is performed is written as a written as a subroutine at the subroutine at the specified location, specified location, the processor the processor performs the task. performs the task. This subroutine is This subroutine is known as a service known as a service routine routine
192192
Computer Architecture
& Microprocessor
SteStep p 7:7:
You shut your You shut your roommate’s roommate’s windows windows
The service routine The service routine should include the should include the instruction EI to instruction EI to enable the enable the interrupt again. interrupt again. This is similar to This is similar to putting the putting the receiver back on receiver back on the hook the hook
SteStep p 8:8:
You go back your You go back your book, find your book, find your mark, and start mark, and start reading again reading again
At the end of the At the end of the subroutine, the subroutine, the RET instruction RET instruction retrieves the retrieves the memory address memory address where the program where the program was interrupted was interrupted and continues the and continues the execution. execution.
To implement Step 4 in the interrupt process, insert one of RST instructions in the microprocessor by using external hardware and the signal INTA (Interrupt Acknowledge)
193193
Computer Architecture
& Microprocessor
Buffer to enable RST 5Buffer to enable RST 5
194194
Computer Architecture
& Microprocessor8085 Interrupt & Vector 8085 Interrupt & Vector LocationsLocations
195195
Computer Architecture
& Microprocessor
Instruction to Read & Write Instruction to Read & Write InterruptsInterrupts
OP OP CodeCode
OperOperandand
BytByteses
DescriptionDescription
SIMSIM NoneNone 11 Multipurpose Instruction Multipurpose Instruction and used to implement and used to implement the 8085 interrupts and the 8085 interrupts and Serial Data OutputSerial Data Output
RIMRIM NoneNone 11 Multipurpose Instruction Multipurpose Instruction and used to read the and used to read the 8085 interrupts and 8085 interrupts and Serial Data InputSerial Data Input
DD77 DD66 DD55 DD44 DD33 DD22 DD11 DD00
SOSODD
SDSDEE
XXXXXX
R7R7.5.5
MMSESE
MM7.7.55
MM6.6.55
MM5.5.55
SIM Data Bytes
Serial Output data
Serial Data Enable1 = Enable0 = Disable
Don’tCare
Reset RST 7.5If D4 = 1
Mask Set EnableD3 = 1 Mask Interrupts
If bits = 1
196196
Computer Architecture
& Microprocessor
DD77 DD66 DD55 DD44 DD33 DD22 DD11 DD00
SISIDD
I 7I 7 I I 66
I 5I 5 IEIE 7.7.55
6.6.55
5.5.55
RIM Data Bytes
Serial Input Data
Pending Interrupts1 = Pending
Interrupt Enable 1 = Enable
Interrupt Masks1 = Masked
Instruction Set to enable all the interrupts of 8085
EI ;Enable InterruptsMVI A, 08H ;Load bit pattern to enable RST 7.5, 6.5 and 5.5SIM ;Enable RST 7.5, 6.5 and 5.5
197197
Computer Architecture
& MicroprocessorAssuming the microprocessor is completing an RST 7.5 Assuming the microprocessor is completing an RST 7.5 interrupt request, check to see if RST 6.5 is pending. If interrupt request, check to see if RST 6.5 is pending. If it is pending, enable RST 6.5 without affecting any it is pending, enable RST 6.5 without affecting any other interrupts; otherwise, return to the main other interrupts; otherwise, return to the main program. program.
RIMRIM ;Read interrupt mask.;Read interrupt mask.MOV B,AMOV B,A ;Save mask information;Save mask informationANI 20HANI 20H ;Check whether RST 6.5 is pending;Check whether RST 6.5 is pendingJNZ NEXTJNZ NEXTEIEIRETRET ;RST 6.5 is not pending, return to main program.;RST 6.5 is not pending, return to main program.
NEXT:NEXT: MOV A, BMOV A, B ;Get bit patter, RST 6.5 is pending.;Get bit patter, RST 6.5 is pending.ANI 0DHANI 0DH ;Enables RST 6.5 by setting D1 = 0.;Enables RST 6.5 by setting D1 = 0.ORI 08HORI 08H ;Enable SIM by setting D3 = 1;Enable SIM by setting D3 = 1SIMSIMJMP SERVJMP SERV ;Jump to service routine for RST 6.5;Jump to service routine for RST 6.5
198198
Computer Architecture
& MicroprocessorSerial I/OSerial I/O I/O requirementsI/O requirements
• I/O Mapped & Memory Mapped I/O Mapped & Memory Mapped
TransmissionTransmission• Synchronous Vs. AsynchronousSynchronous Vs. Asynchronous• Simplex & Duplex (Half or Full)Simplex & Duplex (Half or Full)
• Parity Check (Odd or Even) with bit DParity Check (Odd or Even) with bit D7 7 = 1: Even= 1: Even
BAUDBAUD• No. of Signals / SecondNo. of Signals / Second
Modem Modem • FSK (Send bits according to frequency)FSK (Send bits according to frequency)
199199
Computer Architecture
& Microprocessor8155/8156 Programmable I/O & 8155/8156 Programmable I/O &
Timer Timer FeaturesFeatures 40 Pins40 Pins
256 Bytes of R/W Memory 256 Bytes of R/W Memory
3 Programmable I/O Ports3 Programmable I/O Ports• Two 8-bit parallel I/O ports (A and B) Two 8-bit parallel I/O ports (A and B) • One 6-bit port (C) One 6-bit port (C)
Programmable 14 bit binary counter / Timer Programmable 14 bit binary counter / Timer
Multiplexed Address & Data BusesMultiplexed Address & Data Buses
200200
Computer Architecture
& MicroprocessorPin ConfigurationPin Configuration
PC3
PC4
TIMER IN
RESET
PC5
TIMER OUT
IO/M
CE
RD
WR
ALE
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
Vss
Vcc
PC1
PC2
PC0
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
8155 / 8156
1
2
3
4
5
6
7
8
9
10
11
12
14
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
201201
Computer Architecture
& MicroprocessorBlock DiagramBlock Diagram
8155
256 X 8Static RAM
A
B
CTimer
8
8
6
Port A
Port B
Port C
PA0-7
PB0-7
PC0-5
AD0-7
IO/M
CE
ALE
RD
WR
RESET
Timer CLK
TIMER OUT
Vcc (+5V)Vss (0V)
202202
Computer Architecture
& MicroprocessorExpanded Block DiagramExpanded Block Diagram
AD7
AD0
PortA
PortB
PortC
TimerLSB
TimerMSB
Data Bus
Con
trol
R
egis
ter
54
Internal 3Decoder2
10
Inte
rnal
La
tch
A1
A2
A3
Timer MSB
Timer MSB
Port C
Port B
Port A
Control Register
A7
CE
203203
Computer Architecture
& Microprocessor Port Address APort Address A15 15 – A– A88 is duplicated by A is duplicated by A77 – A – A00
AA1515 & A & A1414 are Active Low Enable are Active Low Enable AA1313, A, A1212 & A & A1111 are give as input to 8205 decoder are give as input to 8205 decoder OO44 is give to the chip enable of 8155 is give to the chip enable of 8155
AA
22
AA
11
AA
00
ControlControl
00 00 00 Control RegisterControl Register
00 00 11 Port APort A
00 11 00 Port BPort B
00 11 11 Port CPort C
11 00 00 Timer LSBTimer LSB
11 00 11 Timer MSBTimer MSB
204204
Computer Architecture
& Microprocessor
205205
Computer Architecture
& Microprocessor
To enable o4 of 8205 ATo enable o4 of 8205 A1313=1, A=1, A1212=0, =0, AA1111=0=0
The Following table give the address The Following table give the address of Ports of 8155of Ports of 8155
AA
1313
AA
1212
AA
1111
AA
22
AA
11
AA
00
HEX HEX CodeCode
ControlControl
11 00 00 00 00 00 20 H20 H Control Control RegisterRegister
11 00 00 00 00 11 21 H21 H Port APort A
11 00 00 00 11 00 22H22H Port BPort B
11 00 00 00 11 11 23H23H Port CPort C
11 00 00 11 00 00 24H24H Timer Timer LSBLSB
11 00 00 11 00 11 25H25H Timer Timer MSBMSB
206206
Computer Architecture
& MicroprocessorControl RegisterControl Register
DD77 DD66 DD55 DD44 DD33 DD22 DD11 DD00
00 NOP
01 STOP/NOP
10 STOP after TC
11 START
IEA IEB
1 – Enable0 – Disable
DD
33
DD
22
PPCC55
PPCC44
PCPC
33
PPCC22
PPCC11
PCPC
00
00 00 II II II II II II
11 11 OO OO OO OO OO OO
00 11 OO OO OOSTST
BBAA
BFBF
AA
INTINT
RRAA
11 00STST
BBBB
BFBF
BB
INTINT
RRBB
STST
BBAA
BFBF
AA
INTINT
RRAA
Port A Port B
0 – Input ; 1 - Output
207207
Computer Architecture
& MicroprocessorInterfacing 7 segment LED Interfacing 7 segment LED DisplayDisplay
Design 2 7-segment LED displays using Ports A & B of Design 2 7-segment LED displays using Ports A & B of 8155 to display the data bytes.8155 to display the data bytes.
SolutionSolution
HP 5082/7340 are inbuilt decoders- is attached to Port AHP 5082/7340 are inbuilt decoders- is attached to Port A
9370 decoder & 7-segment LEDs is attached with Port B9370 decoder & 7-segment LEDs is attached with Port B
The Data Byte separated into nibbles and displayedThe Data Byte separated into nibbles and displayed
208208
Computer Architecture
& Microprocessor
209209
Computer Architecture
& Microprocessor Control WordControl Word
ProgramProgram
MVI A, 03HMVI A, 03H ; Initialize ports A and B as output ports.; Initialize ports A and B as output ports.OUT 20HOUT 20HMVI A, BYTE1MVI A, BYTE1OUT 21HOUT 21H ; Display BYTE1 at port A.; Display BYTE1 at port A.MVI A, BYTE2MVI A, BYTE2OUT 22HOUT 22H ; Display BYTE2 at port B.; Display BYTE2 at port B.HLTHLT
DD77 DD66 DD55 DD44 DD33 DD22 DD11 DD00
00 00 00 00 00 00 11 11= 03H
No Effect on Timer
NotApplicable
Port CIs not
Being used
Port BAs
O/P
Port AAs
O/P
210210
Computer Architecture
& Microprocessor
Timer in 8155Timer in 8155
Two 8bit RegistersTwo 8bit Registers
14 bits are used for counters14 bits are used for counters
2 bits for Timer Mode2 bits for Timer Mode
Timer can be stoppedTimer can be stopped• At midst of Terminal CountAt midst of Terminal Count• At end of Terminal CountAt end of Terminal Count
211211
Computer Architecture
& Microprocessor
TimerTimer
MM
22
MM
11
TT11
33
TT11
22
TT11
11
TT11
00
TT
99
TT
88
TT
77
TT
66
TT
55
TT
44
TT
33
TT
22
TT
11
TT
00
MM
22
MM
11
DescriptionDescription
00 00 One Square One Square WaveWave
00 11 Continuous Continuous Square WaveSquare Wave
11 00 Single Pulse Single Pulse upon TCupon TC
11 11 Continuous Continuous Pulse upon Pulse upon every TCevery TC
212212
Computer Architecture
& MicroprocessorExample for using TimerExample for using Timer
11 00 11 11 11 00 00 00
00 11 00 00 11 00 11 11
11 11 00 00 11 11 11 00
The System Clock is connected to Timer IN of 8155. The clock has 3MHz Frequency. Write a program to produce continuous square wave with a frequency of 1KHz. Includes a start timer command, disable the port interrupts, make Port B&C as O/P ports and make Port A as I/P port.
LSB Timer
MSB Timer
Control Word
• Timer • 300010 = 0BB8H• Timer M2, M1 = 0,1 (Continuous Square Wave)
• Control Word• D0, D1, D2 & D3 = 0,1,1&1 respectively (Port A is I/P & Port B&C are O/P• D6, D7 = 1, 1 (Start the Timer)
213213
Computer Architecture
& Microprocessor
ProgramProgram
MVI A, B8HMVI A, B8H -- Setting LSB of TimerSetting LSB of Timer
OUT 24HOUT 24H -- Loading LSB TimerLoading LSB Timer
MVI A, 4BHMVI A, 4BH -- Setting MSB TimerSetting MSB Timer
OUT 25HOUT 25H -- Loading MSB TimerLoading MSB Timer
MVI A, CEHMVI A, CEH -- Setting Control WordSetting Control Word
OUT 20HOUT 20H -- Loading Control WordLoading Control Word
214214
Computer Architecture
& Microprocessor
8355 / 87558355 / 8755
2K memory of EPROM2K memory of EPROM
2 8-bit I/O Ports2 8-bit I/O Ports
Data Direction RegisterData Direction Register
215215
Computer Architecture
& MicroprocessorPin ConfigurationPin Configuration
CE1
CE2
CLK
RESET
N.C.
READY
IO/M
IOR
RD
IOW
ALE
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
Vss
Vcc
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
A10
A9
A8
8355 / 8755
1
2
3
4
5
6
7
8
9
10
11
12
14
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
216216
Computer Architecture
& MicroprocessorBlock DiagramBlock Diagram
8355/8755
2K X 8EPROM
A
B
8
8
Port A
Port B
PA0-7
PB0-7
AD0-7
READY
CE2
ALE
RD
IOWRESET
Prog/CE1
VDD
VCC
VSS
CLK
IOR
IO/M
A8-10
217217
Computer Architecture
& Microprocessor
218218
Computer Architecture
& Microprocessor
Address BitsAddress Bits
AA11
55//AADD
77
AA11
44//AADD66
AA11
33//AADD
55
AA11
22//AADD
44
AA11
11//AADD
33
AADD
22
AADD
11
AADD
00
SelecteSelected d
RegisterRegister
00 00 00 00 00 XX 00 00 Port APort A
00 00 00 00 00 XX 00 11 Port BPort B
00 00 00 00 00 XX 11 00 DDR ADDR A
00 00 00 00 00 XX 11 11 DDR BDDR B
219219
Computer Architecture
& Microprocessor
Interfacing 8755 I/O PortsInterfacing 8755 I/O Ports
220220
Computer Architecture
& Microprocessor
ExampleExample
Write initialization instructions to configure port A Write initialization instructions to configure port A and port B as output ports, and display 32H at port A and port B as output ports, and display 32H at port A
Program:Program:
MVI A, FFHMVI A, FFH ; Control word to set up all bits as ; Control word to set up all bits as output bitsoutput bits
OUT 02HOUT 02H ; Initialize port A as output; Initialize port A as output
OUT 03HOUT 03H ; Initialize port B as output; Initialize port B as output
MVI A, 32HMVI A, 32H
OUT 00HOUT 00H ; Display 32H at port A; Display 32H at port A
HLTHLT
221221
Computer Architecture
& Microprocessor8279 Programmable Keyboard / 8279 Programmable Keyboard / Display InterfaceDisplay Interface
Simultaneous Keyboard Display OperationSimultaneous Keyboard Display Operation
8 character keyboard FIFO8 character keyboard FIFO
2-key lockout or N-Key Roll over2-key lockout or N-Key Roll over
Dual 8 or 16 numerical DisplayDual 8 or 16 numerical Display
Single 16 character displaySingle 16 character display
Right or Left Entry 16 Byte display RAMRight or Left Entry 16 Byte display RAM
222222
Computer Architecture
& Microprocessor
Major SegmentsMajor Segments
KeyboardKeyboard• Connected to 64 contact key matrixConnected to 64 contact key matrix• Entries are stored in FIFOEntries are stored in FIFO• Interrupt sent for every entryInterrupt sent for every entry
DisplayDisplay• Has 16 characters scanned displayHas 16 characters scanned display• 16 character memory16 character memory
223223
Computer Architecture
& MicroprocessorPin ConfigurationPin Configuration
RL2
RL3
CLK
IRQ
RL4
RL5
RL6
RL7
RESET
RD
WR
DB0
DB1
DB2
DB3
DB4
DB5
DB6
DB7
Vss
Vcc
RL1
RL2
CTRL/STB
SHIFT
SL3
SL2
SL1
SL0
OUT B0
OUT B1
OUT B2
OUT B3
OUT A0
OUT A1
OUT A2
OUT A3
BD
CS
A0
8279
1
2
3
4
5
6
7
8
9
10
11
12
14
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
224224
Computer Architecture
& Microprocessor
IRQ RL0-7
DataBus
SHIFTRD
CNTL/STBWR
CS
SL0-3
A0
OUT A0-3
RESET
OUT B0-3
CLK BD
Logical SymbolLogical Symbol
8
8
4
4
4
Vcc
Vss
Scan
Display
Data
Key Data
CPU
Interface
225225
Computer Architecture
& MicroprocessorPin NamesPin Names
DBDB00
-7-7
I/I/OO
Data Bus (Bi Data Bus (Bi Directional)Directional)
CLKCLK II Clock InputClock Input
RESRESETET II Reset InputReset Input
CSCS II Chip SelectChip Select
RDRD II Read InputRead Input
WRWR II Write InputWrite Input
A0A0 IIBuffer Buffer AddressAddress
IRQIRQ OOInterrupt Interrupt Request Request OutputOutput
SLSL0-30-3 OO Scan LinesScan Lines
RLRL0-30-3 IIReturn Return LinesLines
SHIFTSHIFT II Shift InputShift Input
CNTL/CNTL/STBSTB II
Control Control Strobe Strobe InputInput
OUT OUT AA0-30-3
OODisplay (A) Display (A) OutputsOutputs
OUT OUT BB0-30-3
OODisplay (B) Display (B) OutputsOutputs
BDBD OOBlank Blank Display Display OutputOutput
226226
Computer Architecture
& MicroprocessorLogic Block DiagramLogic Block Diagram
227227
Computer Architecture
& Microprocessor
Different SectionsDifferent Sections Keyboard SectionKeyboard Section
Scan SectionScan Section
Display SectionDisplay Section
MPU Interface SectionMPU Interface Section
228228
Computer Architecture
& Microprocessor
Programming 8279Programming 8279
left or right entry and key rollover.left or right entry and key rollover.
clock frequency prescaler.clock frequency prescaler.
starting address and incrementing mode of the starting address and incrementing mode of the FIFO RAM.FIFO RAM.
RAM address to read and write data and RAM address to read and write data and incrementing mode.incrementing mode.
blanking format.blanking format.
229229
Computer Architecture
& Microprocessor
230230
Computer Architecture
& Microprocessor
CircuitCircuit
The 8279 Programmable Keyboard / Display InterfaceThe 8279 Programmable Keyboard / Display Interface
A Matrix keyboard with 22 keysA Matrix keyboard with 22 keys
Six seven-segment LEDs: DS1-DS6Six seven-segment LEDs: DS1-DS6
74LS156 decoder with open collector outputs.74LS156 decoder with open collector outputs.
Transistors as current DriversTransistors as current Drivers
8205 decoder for the decoding logic8205 decoder for the decoding logic
231231
Computer Architecture
& Microprocessor
Port AddressPort Address
Keyboard/Display ModeKeyboard/Display Mode
MVI A, 00HMVI A, 00H Control word to set mode: LeftControl word to set mode: Left 0 0 0 D D 0 0 0 D D K K KK K K
entry, 8-character, 2-key lockoutentry, 8-character, 2-key lockout
encoded scan keyboardencoded scan keyboard
STA 1900HSTA 1900H Initialize 8279Initialize 8279
232232
Computer Architecture
& MicroprocessorPUSH HPUSH H
PUSH PSWPUSH PSWRead FIFO RAM: Control WordRead FIFO RAM: Control Word
LXI H, 1900HLXI H, 1900H Keyboard controlKeyboard control 0 1 0 A1 X A 0 1 0 A1 X A A AA A
register addressregister address
MVI M, 40HMVI M, 40H Control word to readControl word to read
from keyboardfrom keyboard
DCR HDCR H Data Port Address 1800HData Port Address 1800H
MOV A, MMOV A, M Read data Data Format D7 D6 D5 D4 D3 D2 D1 D0Read data Data Format D7 D6 D5 D4 D3 D2 D1 D0
ANI 3FHANI 3FH Mask D7 and D6.Mask D7 and D6. CNTL SHFT ROW COL CNTL SHFT ROW COL
CNTL, Shift keys areCNTL, Shift keys are
not being usednot being used
STA IBUFFSTA IBUFF Store in R/W memoryStore in R/W memory
POP PSWPOP PSW
POP HPOP H
RETRET
233233
Computer Architecture
& Microprocessor8254 Programmable Interval 8254 Programmable Interval TimerTimer
40 Pin40 Pin 3 independent Counters3 independent Counters 5 Modes of Operations5 Modes of Operations
234234
Computer Architecture
& Microprocessor
Signals of 8254Signals of 8254
235235
Computer Architecture
& Microprocessor
Modes of OperationsModes of Operations
Mode 0Mode 0 Interrupt on Terminal CountInterrupt on Terminal Count
• Count Begins one clock pulse after the count Count Begins one clock pulse after the count has been written in to counterhas been written in to counter
• GATE 0 = 1, then counter 0 counts downGATE 0 = 1, then counter 0 counts down• CLK 0 pulse then the counter decrements by CLK 0 pulse then the counter decrements by
11• GATE 0 = 0. then counts inhibitedGATE 0 = 0. then counts inhibited
The operation is same for all the 3 The operation is same for all the 3 counterscounters
236236
Computer Architecture
& Microprocessor
Read/Write OperationsRead/Write Operations
237237
Computer Architecture
& Microprocessor
Control WordControl Word
238238
Computer Architecture
& Microprocessor
Memory, Port & Timer AddressMemory, Port & Timer Address
239239
Computer Architecture
& Microprocessor
Control Word for 8255A#1Control Word for 8255A#1
240240
Computer Architecture
& Microprocessor
Control Word for 8255A#2Control Word for 8255A#2
241241
Computer Architecture
& Microprocessor
Control Word for 8254Control Word for 8254
242242
Computer Architecture
& Microprocessor
ProgramProgram
MVIMVI A, CWR1A, CWR1 ;Get 8255A #1command word;Get 8255A #1command word
OUTOUT CR1CR1
MVIMVI A, CWR2A, CWR2 ;Get 8255A #2 command word;Get 8255A #2 command word
OUTOUT CR2CR2
MVIMVI A, BLMSETA, BLMSET ;Get byte to blank the LIMIT SET ;Get byte to blank the LIMIT SET lamp.lamp.
OUTOUT PORTC2PORTC2 ;Send to port C of 8255 #2;Send to port C of 8255 #2
CALL CALL RALARMRALARM ;Reset alarms.;Reset alarms.
CALL CALL STCNTR0STCNTR0 ;Start counter 0.;Start counter 0.
EIEI ;Enable interrupts;Enable interrupts
RETRET ;End of subroutine.;End of subroutine.
243243
Computer Architecture
& Microprocessor
Temperature Monitoring System Temperature Monitoring System
General ControlsGeneral Controls
µprocessor based system is designed to control the µprocessor based system is designed to control the temperature of a water bath, by controlling a heater ON temperature of a water bath, by controlling a heater ON or OFFor OFF
Accuracy of Accuracy of 1º C 1º C
Temperatures can be set by switchesTemperatures can be set by switches
7 segment Display is used to display the temperature7 segment Display is used to display the temperature
This involves both hardware & software designThis involves both hardware & software design
244244
Computer Architecture
& Microprocessor
Hardware DesignHardware Design A transducer is used to convert temperature into an A transducer is used to convert temperature into an
equivalent analog electrical quantityequivalent analog electrical quantity
The analog signal is converted in digital by A/D ConvertersThe analog signal is converted in digital by A/D Converters
A relay is used to switch heater ON & OFFA relay is used to switch heater ON & OFF
Two digit 7-segment display is used to display the Two digit 7-segment display is used to display the temperaturetemperature
All these hardware are interface to MPU through I/O portsAll these hardware are interface to MPU through I/O ports
EPROM is used to store the SoftwareEPROM is used to store the Software
245245
Computer Architecture
& MicroprocessorBlock Diagram of Hardware Block Diagram of Hardware
DesignDesign
Address, Data & Control Busses
MPU
EPROM8 Bit
I/O Port
Relay Driver &
Relay
8 bitI/O Port
8 BitI/O Port
Temp. Transducer
& Buffer
A/D Converter
7-segment Displays
Switches
SO
DSID
246246
Computer Architecture
& MicroprocessorDetailed Block DiagramDetailed Block Diagram
247247
Computer Architecture
& Microprocessor
248248
Computer Architecture
& Microprocessor MemoryMemory
• No RAM is necessaryNo RAM is necessary• EPROM 2716 is used to used (2KB of Memory)EPROM 2716 is used to used (2KB of Memory)
I/O PortI/O Port• System requires 26 I/O lines (17 O/P & 9 I/P)System requires 26 I/O lines (17 O/P & 9 I/P)• 8255 (24 Ports) with SID & SOD8255 (24 Ports) with SID & SOD
A/D ConverterA/D Converter• ADC chips are quite costlier when compared to ADC chips are quite costlier when compared to
DAC. As fast conversion is not necessaryDAC. As fast conversion is not necessary• ADC can be implemented by using an external ADC can be implemented by using an external
DAC and a comparator with MPU as ControllerDAC and a comparator with MPU as Controller
249249
Computer Architecture
& Microprocessor LED DisplayLED Display
• 2 7-segment display is used 2 7-segment display is used
SwitchesSwitches• One Thumb wheel Switch is used(4 toggle switches)One Thumb wheel Switch is used(4 toggle switches)
Transducer & BufferTransducer & Buffer• A thermistor with 5KA thermistor with 5K is used at 25 is used at 25ºCºC
Relay & relay driverRelay & relay driver• Temperature of Bath is controlled by immersion heater Temperature of Bath is controlled by immersion heater
ON or OFFON or OFF• Immersion heater is ON or OFF by a relayImmersion heater is ON or OFF by a relay• This controlled by SID & SOD of MPUThis controlled by SID & SOD of MPU
250250
Computer Architecture
& Microprocessor
Software Design (Algorithm)Software Design (Algorithm) Initialize I/O port of 8255.Initialize I/O port of 8255.
ADC is performed by successive approximationADC is performed by successive approximation
Getting Temperature for Bath.Getting Temperature for Bath.
Display measured temperature in LED Display Display measured temperature in LED Display
Read the desired temperature from SwitchesRead the desired temperature from Switches
Comparing measured temp. with desired temp. & making Comparing measured temp. with desired temp. & making SOD low or high SOD low or high
Generate a delay of 2 SecondGenerate a delay of 2 Second
251251
Computer Architecture
& MicroprocessorFlowchartFlowchartStart
Initialize I/O ports
A/D Converter
Get Desired Temp.
Display measured Temp
Read Desired Temp.
Make RelayOFF
.5 Sec Delay
Make RelayON
Is MT = DT
Yes
NO
252252
Computer Architecture
& MicroprocessorProgramProgram
MVI A, MVI A, 89H89H Initialize Port A & B as Initialize Port A & B as
O/P, C as I/PO/P, C as I/POUT OUT 03H03H
AGAIAGAIN:N:
MVI MVI C,00HC,00H Initial Data ValueInitial Data Value
REP:REP: MOV A, MOV A, CC
Send to DACSend to DACOUT OUT 00H00H
MVI D, MVI D, 08H08H
Wait for DACWait for DACDCR DDCR D
JNZ JNZ LOOPLOOP
RIMRIM Get Comparator O/PGet Comparator O/P
RALRAL
Check for non-EqualityCheck for non-EqualityJNC JNC COUNTCOUNTDD
JMP JMP NEXTNEXT Check for EqualityCheck for Equality
COUNCOUNTD:TD:
INR CINR CSend next Digital Send next Digital ValueValueJMP JMP
REPREP
NEXTNEXT::
MOV L, MOV L, CC Table starts from Table starts from
0200H0200HMVI H, MVI H, 02H02H
MOV A, MOV A, MM
Get temp. from TableGet temp. from Table
253253
Computer Architecture
& MicroprocessorProgramProgram
OUT OUT 01H01H Display itDisplay it
IN 02HIN 02H Get switch settingGet switch setting
CMP MCMP M Compare Temp. in Compare Temp. in Mem. & Acc.Mem. & Acc.
JC JC OFFOFF If Temp. is High or If Temp. is High or Equal OFF relayEqual OFF relayJZ JZ OFFOFF
ON:ON: MVI A, MVI A, 40H40H
Else ON relayElse ON relaySIMSIM
JMP JMP DELAYDELAY
OFF:OFF: MVI A, MVI A, C0HC0H Switching OFF relaySwitching OFF relaySIMSIM
DELADELAY:Y:
MVI D, MVI D, 00H00H
Time DelayTime Delay
L2:L2: MVI E, MVI E, 00H00H
L1:L1: DCR EDCR E
JNZ JNZ L1L1
DCR DDCR D
JNZ JNZ L2L2
JMP JMP AGAINAGAIN
Goto AGAIN to repeat Goto AGAIN to repeat the stepsthe steps