Introduction to Computers

Rabie A. Ramadan, PhD

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Class Information Website

http://www.rabieramadan.org/classes/2012/intro/

Computing Evolution

We Have Come a Long Way!!

The Electronic Numerical Integrator and Computer (ENIAC) begins in 1938

Home computer as imagined more than 50 years ago

The Computer Evolution

Mainframe

Computer, 1960

The P

C, 198

0

Mob

ile

Compu

ter 1

990

Senso

r

Platfo

rms 2

000

Smar

t Dus

t …

Mini-Computer, 1

970

Moore’s Law

1965 prediction by Intel cofounder Gordon Moore:

The number of transistors that can be built on the same size piece of silicon will double every 18 months

year

log

(p

eop

le p

er

com

pu

ter)

Streaming Data to/from the

Physical World

Excerpted from ‘The Mote Revolution: Low Power Wireless Sensor Network’, UCB, 2004.

Bell’s Law: New computing class every 10 years

Ubiquitous Computing: A Vision Ahead of its Time

The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it.

Mark Weiser, 1991

Why Computers?

CRT Display

Keyboard

Mouse

“The Box”CD-ROM Drive

FloppyDiskDrive

Inside “The Box”

Motherboard

CPU(Central Processing Unit)

SIMM(Single Inline Memory Module)

HDD(Hard Disk Drive)

Power Supply

Schematic Diagram of a Personal Computer...

Ports

CPU

RAM

Diskcontroller

Graphicscard

Soundcard

Networkcard

Printer

Mouse

Keyboard

Modem Monitor

Speakers

bus

Computer

“Other” Computing

BIOS CHIP

A BIOS chip (Basic Input Output System) is a very important computer component.

In simple terms, the BIOS chip wakes up the computer when you turn it on and reminds it what parts it has and what they do!

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Memory -- "How the processor stores and uses immediate data“

RAM - Random Access Memory• The main 'working' memory used by the computer.

• When the operating system loads from disk when you first switch on the computer, it is copied into RAM.

• As a rough rule, a Microsoft Windows Microsoft Windows based computer will operate faster if you install more RAM. Data and programs stored in RAM are volatilevolatile (i.e. the information is lost when you switch off the computer).

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Memory

ROM – Read Only Memory• Read Only Memory (ROM) as the name suggests is a

special type of memory chip that holds software that can be read but not written to.

• A good example is the ROM-BIOS chip, which contains read only software.

• Often network cards and video cards cards and video cards also contain ROM chips.

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How Computer Memory Is Measured?

Bytes, Kilobytes,Megabytes and Gigabytes

Byte 8 Bits=1 byte KB Kilobyte=1,000 bytes MB Megabyte=1,000,000

(1 million) bytes GB Gigabyte=1,000,000,000

(1 billion) bytes

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Number Systems

Number Systems The on and off states of the capacitors in RAM can be

thought of as the values 1 and 0, respectively.

Therefore, thinking about how information is stored in RAM requires knowledge of the binary (base 2) binary (base 2) number system.number system.

Let’s review the decimal (base 10) number system decimal (base 10) number system first.

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The Decimal Number System

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• The decimal number system is a positional number system.

• Example: 5 6 2 1 1 X 100 = 1 103 102 101 100 2 X 101 = 20 6 X 102 = 600 5 X 103 = 5000

The Decimal Number System (con’t)

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• The decimal number system is also known as base 10.

• The values of the positions are calculated by taking 10 to some power.

• Why is the base 10 for decimal numbers?o Because we use 10 digits, the digits 0 through 9.

The Binary Number System

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• The binary number system is also known as base 2.

• The values of the positions are calculated by taking 2 to some power.

• Why is the base 2 for binary numbers?o Because we use 2 digits, the digits 0 and 1.

The Binary Number System (con’t)

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• The binary number system is also a positional numbering system.

• Instead of using ten digits, 0 - 9, the binary system uses only two digits, 0 and 1.

• Example of a binary number and the values of the positions: 1 0 0 1 1 0 1 26 25 24 23 22 21 20

Converting from Binary to Decimal

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1 0 0 1 1 0 1 1 X 20 = 1 26 25 24 23 22 21 20 0 X 21 = 0 1 X 22 = 4 20 = 1 24 = 16 1 X 23 = 8 21 = 2 25 = 32 0 X 24 = 0 22 = 4 26 = 64 0 X 25 = 0 23 = 8 1 X 26 = 64

7710

Converting from Binary to Decimal (con’t)

Practice conversions:

Binary Decimal

11101

1010101

100111

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Converting From Decimal to Binary (con’t)

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• Make a list of the binary place values up to the number being converted.

• Perform successive divisions by 2, placing the remainder of 0 or 1 in each of the positions from right to left.

• Continue until the quotient is zero.

• Example: 4210

25 24 23 22 21 20

32 16 8 4 2 1

1 0 1 0 1 0

Decimal ‒to‒ Binary ConversionThe Process : Successive Division

a)Divide the Decimal Number by 2; the remainder is the LSB of Binary Number .

b) If the quotation is zero, the conversion is complete; else repeat step (a) using the quotation as the Decimal Number. The new remainder is the next most significant bit of the Binary Number.

Example:

Convert the decimal number 610 into its binary equivalent.

Bit tSignifican Most 1 r 0 1 2

1 r 1 3 2

Bit tSignifican Least 0 r 3 6 2

610 = 1102

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Dec → Binary : Example #1

Example:

Convert the decimal number 2610 into its binary equivalent.

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Dec → Binary : Example #1Example:

Convert the decimal number 2610 into its binary equivalent.

Solution:

LSB 0 r 13 26 2

MSB 1 r 0 1 2

1 r 6 13 2

0 r 3 6 2

1 r 1 3 2

2610 = 110102

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Dec → Binary : Example #2

Example:

Convert the decimal number 4110 into its binary equivalent.

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Dec → Binary : Example #2Example: Convert the decimal number 4110 into its binary equivalent.

Solution:

LSB 1 r 20 41 2

0 r 10 20 2

0 r 5 10 2

1 r 2 5 2

4110 = 1010012

MSB 1 r 0 1 2

0 r 1 2 2

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Dec → Binary : More Examples

a) 1310 = ?

b) 2210 = ?

c) 4310 = ?

d) 15810 = ?

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Converting From Decimal to Binary (con’t)

Practice conversions:

Decimal Binary

59

82

175

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Working with Large Numbers

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0 1 0 1 0 0 0 0 1 0 1 0 0 1 1 1 = ?

• Humans can’t work well with binary numbers; there are too many digits to deal with.

• Memory addresses and other data can be quite large. Therefore, we sometimes use the hexadecimal number system.

The Hexadecimal Number System

The hexadecimal number system is also known as base 16. The values of the positions are calculated by taking 16 to some power.

Why is the base 16 for hexadecimal numbers ?

• Because we use 16 symbols, the digits 0 to 9 and the letters A through F.

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The Hexadecimal Number System (con’t)

Binary Decimal Hexadecimal Binary Decimal Hexadecimal

0 0 0 1010 10 A

1 1 1 1011 11 B

10 2 2 1100 12 C

11 3 3 1101 13 D

100 4 4 1110 14 E

101 5 5 1111 15 F

110 6 6

111 7 7

1000 8 8

1001 9 9

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The Hexadecimal Number System (con’t)

Example of a hexadecimal number and the values of the positions:

3 C 8 B 0 5 1 166 165 164 163 162 161 160

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Example of Equivalent Numbers

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Binary: 1 0 1 0 0 0 0 1 0 1 0 0 1 1 12

Decimal: 2064710

Hexadecimal: 50A716

Notice how the number of digits gets smaller as the base increases.

Significant Digits

Binary: 11101101

Most significant digit Least significant digit

Hexadecimal: 1D63A7A

Most significant digit Least significant digit

Your turn

Convert the following number to Hex ?

0101 1010 1111

0101 0101 01012

10 0101 1010 1111 . 1011 1112 = 2 5 A F . B E16

Dec → Binary : More Examples

a) 1310 = ?

b) 2210 = ?

c) 4310 = ?

d) 15810 = ?

1 1 0 1 2

1 0 1 1 0 2

1 0 1 0 1 1 2

1 0 0 1 1 1 1 0 2

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Binary Addition

4 Possible Binary Addition Combinations:

(1) 0 (2) 0

+0 +1

00 01

(3) 1 (4) 1

+0 +1

01 10

SumCarry

Note that leadingzeroes are frequently

dropped.

Memory Organization

Types of Memory

Cache Memory• Serves as a buffer for frequently accessed data

• Small High Cost

RAM (Main Memory)• Stores programs and data that the computer needs when executing a

program

• Dynamic RAM (DRAM) • Uses Tiny Capacitors

• Needs to be recharged every few milliseconds to keep the stored data

• Static RAM (SRAM)• Holds its data as long as the power is on

• D Flip Flop

Types of Memory (Cont.) ROM

• Stores critical information necessary to operate the system.

• Hardwired can not be programmed

Programmable Read Only Memory (PROM)• Can be programmed once using appropriate equipment

Erasable PROM (EPROM) • Can be programmed with special tool

• It has to be totally erased to be reprogrammed

Electrical Erasable PROM (EEPROM) • No special tools required

• Can erase a portion

Memory Hierarchy

The idea • Hide the slower memory behind the fast memory

• Cost and performance play major roles in selecting the memory.

Hit Vs. Miss Hit

• The requested data resides in a given level of memory.

Miss• The requested data is not found in the given level of memory

Hit rate• The percentage of memory accesses found in a given level of

memory.

Miss rate• The percentage of memory accesses not found in a given level of

memory.

Hit Vs. Miss (Cont.)

Hit time• The time required to access the requested information in a given

level of memory.

Miss penalty• The time required to process a miss,

• Replacing a block in an upper level of memory,

• The additional time to deliver the requested data to the processor.

Miss Scenario

The processor sends a request to the cache for location X• if found cache hit

• If not try next level

When the location is found load the whole block into the cache • Hoping that the processor will access one of the neighbor

locations next.

• One miss may lead to multiple hits Locality Can we compute the average access time based on this

memory Hierarchy?

Average Access Time Assume a memory hierarchy with three levels (L1, L2, and L3)

What is the memory average access time?

h1 hit at L1 (1-h1) miss at L1t1 L1 access time

h2 hit at L2(1-h2) miss at L2t2 L2 access time

h3 hit at L3=100%(1-h3) miss at L3t3 L3 access time

Your Assignment

1. Convert the following numbers to binary : - 198- 2011- 11240

2. Convert the following binary numbers to Hex : - 1111111111111111- 101010101010101

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Your Assignment

3. Write a short essay about the importance of computers in social activities ?

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Thank you