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Lesson 2 How Computers Work
Semester 1 Microcontrollers
Lecturers: Juan Daz
Jorge Garca
Electrical EnergyConversion andPower Systems
Universidadde Oviedo
Presentation:
Ignacio lvarez GarcaISA-Uniovi 2004
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Outline
Introduction
Blocks in a Computer
Instructions execution
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A computer
Machine that executes instructions sequentially Program=sequence
of instructions
Instructions and Data stored in MEMORY Memory organized in
addresses
Instructions, data and operations in BINARY CODE
Read instructionfrom memory
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Content
01101100
00101110
11111100
Instructions in binary code
Data in binary code
11101100
01101101
11101011
00000000
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
0
7
2
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Parts of a computer
Control Unit (CU): organizes theoperation of the computer
Artimetihc-Logic Unit (ALU):executes arithmetic (+,-,*,/)
andlogic (bit level) (AND, OR, )operations
Registers: Temporary places forstoring information
Memory: Main place ofinformation storage (code anddata)
I/O Devices: Allowcommunication with the outerworld
CPU
ALU
CU
registers
Memory
I/O
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Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000000
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
0
7
2
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count. Inst1
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
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Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000000
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
0
7
2
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count. Inst1
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
11101100
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CPU11101100
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000000
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
0
7
2
Instruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count. Inst1
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
MOV X,3
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Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000000
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
0
7
2
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count. Inst1
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
MOV X,3
00000011
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CPU
00000011
MOV X,3
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000000
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
0
7
2
Instruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count. Inst1
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
00000011
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CPU
00000011
00000011
MOV X,3
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000000
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
0
7
2
Instruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count. Inst1
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
00000011 3
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Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
3
7
2
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count. Inst1
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
+1Inst2
00000011
00000011
MOV X,3
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Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
7
2
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
00000011
00000011
MOV X,3
Inst2Inst2
3
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Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
7
2
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
00000011
00000011
Inst211101011
3
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CPU11101011
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
7
2
Instruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
00000011
00000011
Inst2MOV Z,X
3
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CPU
00000011
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
7
2
Instruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
00000011
Inst2MOV Z,X
00000011
3
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CPU
00000011
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
7
2
Instruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2MOV Z,X
00000011
00000011
3
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Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000010
MOV X,3
MOV Z,X
ADD Z,Y
7
2
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2MOV Z,X
00000011
00000011
00000011 3
3
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Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000011
MOV X,3
MOV Z,X
ADD Z,Y
7
3
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2MOV Z,X
00000011
00000011
+1Inst3
3
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Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000011
MOV X,3
MOV Z,X
ADD Z,Y
7
3
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2MOV Z,X
00000011
00000011
Inst3
3
11101011
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11101011
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000011
MOV X,3
MOV Z,X
ADD Z,Y
7
3
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2ADD Z,Y
00000011
00000011
Inst3
3
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11101011
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000011
MOV X,3
MOV Z,X
ADD Z,Y
7
3
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2ADD Z,Y
00000011
00000011
Inst3
3
00000111
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11101011
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000011
MOV X,3
MOV Z,X
ADD Z,Y
7
3
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2ADD Z,Y
00000111
00000011
Inst3
3
00000011
00001010
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11101011
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000011
MOV X,3
MOV Z,X
ADD Z,Y
7
3
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2ADD Z,Y
00000111
00001010
Inst3
3
00000011
00001010 10
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11101011
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000011
MOV X,3
MOV Z,X
ADD Z,Y
7
3
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2ADD Z,Y
00000111
00001010
???
3
00000011
00001010 10
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11101011
Execution of Instructions
Example: x=3; z=x+y;
Address
000..00
000..01
000..10
Inst1:
Inst2:
Inst3:
X:
Y:
Z:
. . .
. . .
. . .
Content
01101100
00101110
11111100
11101100
01101101
11101011
00000011
00000111
00000011
MOV X,3
MOV Z,X
ADD Z,Y
7
3
CPUInstruction:
Operand 1:
Operand 2:
ALU
Result:
Prog. Count.
Read instructionfrom memory
Decodeinstruction
Getoperands
Calculateresult
Store result
Fetch nextinstruction
Inst2ADD Z,Y
00000111
00001010
???
3
00000011
00001010 10
Repeat
