Computer Systems

Computer Systems A.

B.

COMPONENTS:

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Device/method: inputs data

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Circuit boards & programs: process data

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Output Device: displays the result

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Mechanism: stores data

SYSTEM MOTHERBOARD:

 Contains the electronic circuitry of the computer

 6 COMPONENTS:

C.



Primary Processing Chip



Memory Chips



Expansion Slots



Ports to connect external devices



BIOS chips too control system start-up



Circuitry enables components to communicate

CENTRAL PROCESSING UNIT



Brains of computer

 Housed on a silicon chip w/ millions of switches & circuits

 2 PRIMARY SECTIONS:

a. ARITHMETIC/LOGIC UNIT (ALU): 1. Where computations and comparisons takes place

b. CONTROL UNIT: 1. boss of the CPU that coordinates all activity 2. uses programming instructions to control the actions of the CPU 3. programs are written in programming languages that causes on or more actions to occur

D.

COMPUTER MEMORY

 Where data processed by the CPU is stored  Consists of addressable locations w/in the machine that the comp. can access directly  Volatile: when power fails, everything in memory is lost 

E.

Data should be stored in a disk when not being processed.

TYPES OF MEMORY

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RAM (RANDOM ACCESS MEMORY)  Short-term memory

Data is processed while a program is running Data CAN BE accessed and modified Loses data if computer is shut down

•

ROM (READ-ONLY MEMORY)

Tells the computer how to start itself Placed on the motherboard that contains instructions

CAN’T BE accessed or modified by application programs Not lost when shut down

F.

BASIC MACHINE CYCLE FOR PROCESSING A PROGRAM STATEMENT

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INSTRUCTION CYCLE: amount of time to read & decode the instruction

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EXECUTION CYCLE: amount of time to execute the instruction & store the results • ALU: where calculations and comparisons take place

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MACHINE CYCLE: • instruction cycle + one or more execution cycles • Measured in microseconds

G. COMPUTER SYSTEM CONTROLLERS:

H.

•

PC motherboard contains several controllers

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Controls transfer of data between computer and peripheral devices (mouse, printer, monitor, keyboard, etc...)

•

Found on a single chip that can handle all common devices

PORTS: •

Connects peripheral devices to the computer circuitry

a.SERIAL DEVICES (mice, monitor, ...) •

Transmits data one bit at a time.

b.PARALLEL DEVICES (printers) •

Transmits data several bits at a time.

c. USB •

Newer, high-speed method

•

Connects up to 127 external devices

d.FIREWIRE •

Connects up to 63 external devices. Transmit data several bits at a time

I.

EXPANSION SLOTS

 Electrical connections that accept circuit cards to perform specific functions  Used to plug in sound cards, video cards, scanners, and other devices  ELECTRICAL PRONGS: plug into the expansion slot to make an electrical connection to the board.

J.

DATA REPRESENTATION:

 Stored in binary in a series of 1s and 0s  Used standardized coding systems (ASCII) to determine a character or number represented by binary digits

 Stored in a series of 8-digit combinations called a byte. ,