Notes on Hardware and Software.
At the highest level, a computer system is composed of hardware and software components. Hardware consists of all the physical devices. All the programs (code) that run on the computer system form the software part. The hardware and software are tightly coupled and they complement each other. Hardware is useless without software and software requires hardware to carry out computations.
Computer Hardware
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.
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.
Computer Categories
System Description
Microcomputers - This a computer which uses a microprocessor as its CPU. Includes PCs (Both Desktops and laptops), etc. They typically have between 1 and 2056Mb of memory (RAM). They process data in anything from 8-bit ro 64-bit chunks.
Minicomputers These are systems designed for multi-user access several terminals. Varies from processing power from a very powerful micro to a small mainframe.
Mini Computers - A rarely used term that indicates a more powerful computer than a PC but not at the level of a Mainframe. This normally refers to 'servers' which consist of similar hardware to that of a PC but normally constructed to a higher specification to allow multiple simultanious connections from users on a network
Mainframes - Supports hundreds of of terminals for multi-user access. Large amount of primary and auxiliray storage.
Supercomputers 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.
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).
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.
Software
Software is a set of instructions that will make a computer perform a task.
There are three types of software:
- System (including BIOS, operating system and utilities)
- Applications
- Programming Languages
You are expected to be able to discuss these types in significant depth. Each type constitutes a topic of it's own over the next few weeks