What is Computer?

clashjudiciousΗλεκτρονική - Συσκευές

8 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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What is Computer?


A calculating machine


A word processor


An electronic drawing board


An electronic game machine


An information processor (produce useful
information)


A general
-
purpose computer


A dedicated computer

(e.g. calculator, game
boy)

Why using Computer?


Fast


Accurate


Reliable


Never get tired


Has large storage


Sharing of data


Effective communication

Basic Computer System


Input Unit


Central Processing Unit (CPU)


Output Unit


Storage Unit

Central Processing Unit


Control Unit (CU)


Send control signals to different parts of
computer to coordinate the processing


Arithmetic and Logic Unit (ALU)


To perform arithmetic calculations


To perform logical operations

Storage Unit


Main Memory (Primary Storage)


To hold data and program currently processed


Data or program must be first loaded to the main
memory before processing


Not permanent


Backing Store (Secondary Storage)


To hold data and program

not

currently processed


Permanent

Main Memory (1)


ROM (e.g. BIOS)


Read Only Memory, cannot be changed


Slower than RAM


Non
-
volatile


RAM


Random Access Memory


Content can be changed, user

s memory


Faster than ROM


Volatile


Main Memory (2)


Cache


A very fast memory, much faster than RAM,
to communicate between CPU and RAM


Registers


A small memory storage to help CPU
processing


The speed is fastest in memory units


Common registers
-

PC, IR, MAR, MDR,
Accumulator, status registers

BIOS


Basic Input Output System


A ROM to store the boot
-
up program of
the computer system


A boot
-
up program contains RAM test
and hardware detection

Components of Computer System


Hardware


The physical components, e.g. keyboard,
mouse


Software


Programs (set of instructions) to control
the hardware to do different jobs.

Types of Computers

-
classified by processing power


Supercomputer


Mainframe computer


Minicomputer


Microcomputer

Types of Computers

-

classified by functions


Server


Workstation


Terminal, Dump Terminal


Personal Computer (PC)

Types of Microcomputers

-
classified by size and usage


Desktop computer


Book
-
size computer


Laptop computer


Notebook computer


Palmtop computer, pocket computer,
Personal Data Assistant (PDA)

Mainframe computers


Front
-
end processor


To handle communications between
terminals


Back
-
end processor


To handle data retrieval to and from the
mainframe computer