Section 1.1
Introduction To Computing
1.1 Computer Hardware
1.1.1 Computer Concepts
A very basic model of a computer would be:
The refined diagram shows the basic components of a computer system.
RAM
Random Access Memeory. Stores loadedprograms and data to be processed. There are
two types: volatile and non-volatile. Unlike non-volatile memory, volatile memory
lost when the computer is switched off or reset.
ROM
Read Only Memory. Stores information about BIOS and startup routines.
1.1.2 Measuring Storage
Both the primary and auxiliary devices have capacity measured in bits, bytes,
kilobytes, megabytes and gigabytes.
A 1 or a 0 is a BInary digiT (Bit).
There are 8 bits in a byte
1024 bytes in a kilobyte
1024 kilobytes in a megabyte
1024 megabytes in a gigabyte
Therefore there are 1,048,576 bytes in a megabyte.
A double density floppy disk holds 720Kb of data. A high density floppy disk
contains about 1.44Mb of data.
Many computers store one character as one byte.
1.1.3 Computer Categories
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System
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Description
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Microcomputers
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This a computer which uses a microprocessor as its
CPU. Includes PCs, laptops etc. They typically have
between 1 and 128Mb of memory (RAM). They process
data in anything from 8-bit ro 64-bit chunks.
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Minicomputers
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These are systems designed for multi-user access
several terminals. Varies from processing power
from a very powerful micro to a small mainframe.
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Mainframes
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Supports hundreds of of terminals for multi-user
access. Large amount of primary and auxiliray storage.
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Supercomputers
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These are the fastest and most expensive systems.
Although they are not multi-user machines, they are
used when a vast amount of processing is to be done.
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1.1.4 Computer Configuration
This term describes the collection of hardware in use. A large computer
configuration would consist of several hundred micros in a building linked together by
cabling to form a local area network (LAN).
1.1.5 Embedded Systems
An embedded system is dedicated to one specific task. They are special purpose
systems.
Embedded systems typically have their programs stored in ROM as opposed to auxiliary
storage and RAM. These programs are referred to as firmware - a combination of software
and hardware.
