Discovering Computers 2012

Your Interactive Guide to the Digital World

Objectives Overview

Differentiate among various styles of system units on desktop computers, notebook computers, and mobile devices Identify chips, adapter cards, and other components of a motherboard Describe the control unit and arithmetic logic unit components of a processor, and explain the four steps in a machine cycle Identify characteristics of various personal computer processors on the market today, and describe the ways processors are cooled Define a bit and describe how a series of bits represents data See Page 209 for Detailed Objectives Discovering Computers 2012: Chapter 4

2

The System Unit

• • • The

system unit

is a case that contains electronic components of the computer used to process data.

Made of metal or plastic to protects the internal components from damage.

All computers have a system unit. It is available in variety of shapes & sizes.

Page 210 Figure 4-1 Discovering Computers 2012: Chapter 4

3

Discovering Computers 2012: Chapter 4

4

The System Unit

• The inside of the system unit on a desktop personal computer includes: Drive bay(s) Power supply Sound card Video card Processor Memory Page 211 Figure 4-2 Discovering Computers 2012: Chapter 4

5

System unit components

      

Processor

computer.

interprets & carries out the basic instructions that operate a

Memory

executed.

holds data waiting to be processed & instruction waiting to be Processor & Memory are connected to a circuit board called the

motherboard.

Adapter cards

are circuit boards that provide connections and functions not built into the motherboard.

Devices outside the system unit often attach to the

ports.

A drive bay

holds one or more disk drive.

The Power supply

provide the computer with the electricity.

Discovering Computers 2012: Chapter 4

6

Motherboard

• • • The

motherboard

is the main circuit board of the system unit.

Contains expansion slots, processor chips, and memory slots Sometimes called a

system board

Page 212 Figure 4-3 Discovering Computers 2012: Chapter 4

7

Motherboard

• • • • • • Most computers use integrated circuits also called chips , for their CPU and main memory.

Memory chips are installed on memory module( card) that fit in a slot on the mother board.

What is a chip ?

Small piece of semi-conducting material on which integrated circuits (IC) are etched.

IC contain many microscopic pathways capable of carrying electrical current.

Each IC can contain millions of elements such as resistors, capacitors, transistors.

Next

Processor

• The

processor

, also called the

central processing unit

(

CPU

), interprets and carries out the basic instructions that operate a computer – Contain a control unit and an arithmetic logic unit (ALU) that work together to perform processing operations

Multi-core processor

Page 213

Dual-core processor

Discovering Computers 2012: Chapter 4

Quad-core processor

9

• • • A dual-core processor is a single chip that contains two separate processors A multi-core processor is a chip with two or more separate processors Each processor on a dual-core/multi-core chip generally runs at a slower clock speed, but increase overall performance Discovering Computers 2012: Chapter 4

10

Processor

Page 213 Figure 4-4 Discovering Computers 2012: Chapter 4

11

CPU operations

The operations typically performed by a CPU are: 1.

2.

3.

1.

CPUs control the reading of programs and input files.

Its activates input unit to read program and data.

2.

Controls the transmission of program & data files from disk to main memory.

CPUs process data according to instructions in a program.

1.

Data can be processed arithmetically- number can be added, subtracted, 2.

3.

multiplied and divided.

Logical tests can be performed on data. E.g., comparison.

Data can be transmitted or copied from one area of primary storage to another.

CPUs control the creation of output. Discovering Computers 2012: Chapter 4

12

Processor

• • The

control unit

that directs and coordinates most of the operations in the computer.

is the component of the processor – Handles the transmission of data into and out of the CPU and supervises its overall operations.

– Its interprets each instruction issued by a program & then initiates the appropriate action to carry out the instruction.

The

arithmetic logic unit

(ALU) performs arithmetic, comparison, and other operations.

Page 214 Discovering Computers 2012: Chapter 4

13

Processor

• For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle Page 215 Figure 4-5 Discovering Computers 2012: Chapter 4

14

For every instruction, a processor repeats a set of four basic operations:

1.

2.

3.

4.

Fetching

process of obtaining a program instruction or data item from memory.

Decoding

process of translating the instruction into signals the computer can execute.

Executing

process of carrying out the commands.

Storing

, if necessary. Means writing the result to memory .

Discovering Computers 2012: Chapter 4

15

Processor

The processor contains

registers

, that temporarily hold data and instructions The

system clock

controls the timing of all computer operations

Page 216 Discovering Computers 2012: Chapter 4

16

Processor

• • • • • • •

Registers

The registers are special storage areas in the CPU.

Their function is to hold instructions, data values, memory addresses of both the instructions and data.

There are 4 basic types of it: CU , ALU Instruction register hold instruction Address register hold address of( data , next instruction ).

Storage register store data retrieved from main memory prior to processing.

Accumulator store the results of arithmetic & logic operations Discovering Computers 2012: Chapter 4

17

Processor

• •

System clock

It generates regular electronic pulses , or ticks, that control the timing of all computer operations ( i.e. set operating pace of components of system unit) Pace of system clock is clock speed . Most clock speeds are in the gigahertz (GHz) range (1 GHz = one billion ticks of system clock per second).



Processing actions occur at each “tick” of the electronic clock.

 

The Speed of the clock determines the speed at which the CPU can process data.

The faster the clock speed, the more instruction the processor can execute per second (hertz).

Discovering Computers 2012: Chapter 4

18

Processor

• Most current personal computers support pipelining – Processor begins fetching a second instruction before it completes the machine cycle for the first instruction Pages 215 – 216 Figure 4-6 Discovering Computers 2012: Chapter 4

19

Processor

• Parallel processing uses multiple processors simultaneously to execute a single program or task – Massively parallel processing involves hundreds or thousands of processors Page 220 Figure 4-11 Discovering Computers 2012: Chapter 4

20

Processor

•

The leading manufacturers of personal computer processor

•

chips are Intel and AMD They often identify their processor chip by a model name or model number.

•

Other leading processor chip manufacturers



Transmeta



IBM



Motorola

–

IBM processor had a different design from the Intel-style processor.

Pages 216 – 217 Figure 4-7 Discovering Computers 2012: Chapter 4

21

Processor

• Determine how you plan to use a new computer before selecting a processor Page 218 Figure 4-8 Discovering Computers 2012: Chapter 4

22

Processor

• • A processor chip generates heat that could cause the chip to burn up Require additional cooling – Heat sinks – Liquid cooling technology Pages 219 - 220 Figures 4-9 – 4-10 Discovering Computers 2012: Chapter 4

23

Data Representation

Analog signals are continuous and vary in strength and quality Digital signals are in one of two states: on or off • Most computers are digital recognize only two discrete states: on or off.

• Use a

binary system

to recognize two states • Use number system with two unique digits: 0 and 1, called

bits

binary digits) (short for Page 221 Discovering Computers 2012: Chapter 4

24

Data Representation

A computer circuit represents the 0 or the 1 electronically by the presence or absence of an electrical charge Eight bits grouped together as a unit are called a byte punctuation marks) . A byte represents a single character in the computer ( numbers, upper or lower case letters, or

Page 221 Figures 4-12 – 4-13 Discovering Computers 2012: Chapter 4

25

Data Representation

• The different combinations of 0s and 1s are defined by patterns called a coding schema .

• There are two coding schemas used to represent data  ASCII—American Standard Code for Information Interchange [Personal Computers – PCS]  EBCDIC—Extended Binary Coded Decimal Interchange Code [Mainframes, Mini-computers] Page 221 Figure 4-14 Discovering Computers 2012: Chapter 4

26

Data Representation

• ASCII is the most widely used coding scheme to represent data Page 221 Figure 4-14 Discovering Computers 2012: Chapter 4

27

Data Representation

Page 222 Figure 4-15 Discovering Computers 2012: Chapter 4

28