Higher National Computing

Howard Anderson, Sharon Yull, Bruce Hellingsworth

• Publisher: Routledge
• Year: 2004
• ISBN:
  9781136398988
• Edition: 2
• Topic: Informatica
• Subtopic: Informatica generale

Higher National Computing 2e is a new edition of this extremely successful course book, updated specifically to cover the compulsory core units of the 2003 BTEC Higher National Computing schemes. Full coverage is given of the four core units for HNC, the two additional core units required at HND, and the Core Specialist Unit 'Quality Systems', common to both certificate and diploma level.Students following the HNC and HND courses will find this book essential reading, as it covers the core material they will be following through the duration of their course. Knowledge-check questions and activities are included throughout, resulting in a clear and straightforward text which encourages independent study.Like the syllabus itself, this book is ideal for students progressing to HNC / HND from GNVQs, as well as A-Level and BTEC National, with content designed to cover the requirements of students following General Computing, Software Engineering and Business IT courses.

1	Computer Platforms

Summary

The aim of this chapter of the book is to provide sufficient technical information to enable users to make informed purchasing or specification decisions without becoming over involved with detail. Each heading will present the information from the user’s point of view and, where necessary, ignore or gloss over the most technical details. For instance, no real attempt will be made to describe the precise working of a disk drive but the benefits of its performance will be outlined. No attempt has been made to cover other aspects of the use of microprocessors such as embedded systems, mobile communications devices, etc. nor to look at larger machines, mainframe computers or other specialized areas. The focus will be on how to buy a PC but with Sufficient content to be at Higher National level.

Introduction

The Edexcel unit says ‘This unit is aimed at IT practitioners who need sufficient knowledge of computer architecture to make rational and commercial decisions on the selection and specification of systems. Learners will learn how to evaluate operating systems in order to create their own operating environment. Many IT practitioners communicate with specialist technical support staff during the specification and planning of systems implementation. This unit aims to give learners the confidence to communicate with technical and non-technical specialists to justify their recommendations.

It is expected that centres will use current personal computer and networking resources. Learners should be encouraged to read current journals to investigate and evaluate new hardware and software developments.’

It is recognized that centres use a diverse range of hardware and software. For this reason, this chapter avoids specific software dependent items as far as possible.

1.1 The Basic Components of a PC

This part of the book is intended to describe the basic parts of a computer ready to fulfil the requirements of Unit 1, i.e. how to buy a PC.

Students who have embarked on an HNC in Computing will not need to be told that there is a monitor, a system box, etc.; all will have used these items, but they will need the knowledge of how to specify each one or to communicate effectively with experienced technicians.

The System box

This contains the motherboard with the CPU or Central Processing Unit, storage devices such as hard drives or CD-ROM drive, the memory, a power supply and any add-on components such as a video card, modem, etc.

Motherboard

So called because older computers were made from a large number of components organized onto several circuit boards. These were plugged into one ‘main’ or motherboard that contained the CPU and the circuits that communicated with the add-on boards. Modern machines have most of the principal components on one board but the name has stuck. The mother-board will house the CPU, the chipset, the memory connectors or expansion buses for the circuits that are still separate and often the I/O (input/ output) ports. The chipset controls DMA or Direct Memory Access, the bus interface, memory, disks, keyboard, I/O ports and timing.

CPU

The CPU is the circuit that is able to execute the instructions stored in the memory. Modern CPUs in the Intel Pentium series and others are able to execute these instructions at high speed and provide considerable computing power in a small component.

Storage

All the instructions and data that form software must at one point be stored. This data is all in the form of logical 1s or 0s and any physical property of any substance or device that will remain in one state or another can be used to store this software. Most hard disks are magnetic devices that store 1s and 0s as changes in the patterns of magnetic particles held on a surface. CD-ROMs hold 1s and 0s by optical patterns on the surface of a simple material. The only real reason why magnetic hard drives are common is that they are cheap, fast and reliable. When newer, faster devices with higher capacity are manufactured, magnetic hard drives may become a thing of the past; purely optical devices hold this promise. The point is, there is nothing special about a hard drive, it is simply a device that can store a large number of 1s and 0s and deliver them to another circuits at an acceptable speed.

Memory

The memory stores software, i.e. program instructions and data. There are two broad kinds with the rather confusing names RAM for Random Access Memory and ROM for Read Only Memory. The problem is that both may be randomly accessed and some kinds of ROM can be written too! The key point is that RAM is volatile, i.e. it loses its data when the power is turned off, ROM does not, it is non-volatile.

Power Supply

The power supply is another misleading name as the power to run the computer usually comes from the mains or from batteries. The job of the power supply is to provide 12 volts to run disk drive motors, etc. and lower (usually 5 or 3.3) volts to run the digital circuits. It must be able to provide enough current to run everything in the machine without overheating and to ensure the voltage is constant with defined limits.

Display

The most commonly used desktop display device is the CRT or Cathode Ray Tube, a device first widely used in the sciences and defence in the 1940s and extremely expensive at that time; they were also very unreliable. Now CRTs are made cheaply by the million and are amongst the most reliable devices in common use. With the rise in use of laptop computers and the need to save desk space, etc., newer screen types have also become available and the marketplace has become extremely competitive with LCD or Liquid Crystal Display screens currently being the most common. The common name for a CRT is a VDU or Visual Display Unit.

Key Fact

If you need to buy a PC or just one of the components, you need to know more about its performance than how it works. A knowledge of how it works will help with your understanding of the performance and some of the difficulties overcome by the maker but this knowledge does not need to be in great detail. The remaining sections in this chapter are intended to provide the required knowledge.

The Hierarchy of Design

You know that computers are binary devices often made with silicon circuits and they work with logical 1s and 0s. It is hard to imagine the connection between this statement and seeing a wordprocessor in action with all the screen colours, text and clickable buttons, i.e. a program in action. To illustrate this, imagine you are given the task of explaining the idea of a ‘city’ to someone who has only ever lived on a desert island and never had need of permanent housing. If you started by describing ‘what is a brick’ and then immediately described the construction of a whole town using bricks, the connection between the small hard brick and the warm and comfortable rows of houses would be very difficult to follow. If you then took the view of a town planner and spoke of where the hospital should be in your town or how to route a road around a village, any connections with bricks would be entirely lost. The trouble is, towns are made of bricks!

The connection between 1s and 0s and tasks such as installing Windows is of a similar nature. The way to overcome this is to think of ‘layers’ of knowledge. Using the brick and the town example, consider these layers:

of bricks and towns	of computer hardware	of computer software
Bricks. Study what a brick is made of, how it is made, how strong it is, what will it cost.	1s and 0s, simple digital circuits and how logical arithmetic can be performed with a circuit.	Boolean logic.
Walls. Study how to mix cement, how of bricks and towns	How a sequence of logical operations can be of computer hardware	How to perform arithmetic with of computer software
to lay bricks to make a wall, how strong is a wall.	achieved with a circuit, how to add, subtract, perform logical AND and OR operations, etc.	simple numbers.
How to make several walls into a building with spaces for windows and doors, etc. How to build a roof.	How to store many logical instructions and feed them in sequence to a circuit that can execute them.	How to perform arithmetic with multiple digit numbers.
How to install all the services a building needs, water, electricity, gas, heating, etc. and to move in the carpets, furniture, etc.	How to accept human inputs by devices such as a keyboard and to display outputs using devices like a colour monitor.	How to handle data such as text and to edit it, i.e. move a sentence within a paragraph.
How to build a row of houses, provide street lighting, public access, etc.	How to provide a complete set of devices such as a mouse, keyboard, printer, CPU etc. and to make them all connect correctly.	How to present a complete set of facilities in a wordprocessor.
How to plan a town, provide libraries, shops, hospital, bus station, etc.	A complete PC.	How to control the entire machine − the operating system.

In normal life, we expect different people to be expert at these different layers, a brick layer is not a town planner. When studying for the HNC in Computing we do not expect you become expert in any one of the layers, rather to understand all the layers in the same way that you can imagine all the tasks required to build a town; specialization will come later in your studies.

What I am asking you to do here is to take on trust that descriptions of the ‘bricks’ will lead to an understanding of the ‘town council’. It just takes some time.

1.2 Elements in the History of Microprocessors

It is said that history is written by the victors. Although this really refers to political history and especially the result of political failure, war, it also applies to vast business areas like computing. Much of the history of computers has been written by the...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright
• Contents
• Introduction
• 1. Computer Platforms
• 2. Systems Analysis
• 3. Programming Concepts
• 4. Concepts of Database Design
• 5. Networking Concepts
• 6. Personal skills Development
• 7. Quality Systems
• Appendix A: Hexadecimal and Other Number Bases
• Appendix B: ASCII Character Set
• Appendix C: Colour
• Appendix D: A Brief Network Glossary
• Mapping of Learning Outcomes
• Answers
• Index