ICT - revision notes.

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CPT 1 Revision

  • Software may be classified as System Software or Application Software.
  • Give three examples of system software (not product names).

operating system;

utility program (or an example of one);

library program;

compiler/assembler/interpreter/translator;

driver;

user interface;

  • Give three examples of application software (not product names).

Payroll;

Stock Control;

Production control;

Sales;

Invoicing;

Word processing;

Spreadsheet;

Database;

Desk top publishing;

Browser;

Or any appropriate application

  • Unicode is another coding system for characters. Why is it not possible to code 27 into
  • the 16 bit word using Unicode?

Unicode is 16 bit code;

  • The above computer system uses the stored program concept. Explain this term.

Machine code instructions/program stored in main memory; A RAM/IAS

Can be replaced by another program at any time;

  • Describe how sound is encoded when it is stored in a computer system

Sound wave is recorded/sampled at regular intervals;

Height/Amplitude/Height/Value of sound wave is represented by a

number/binary code/binary pattern;

  • Give two features of the coding system that will affect the quality of the sound that is
  • reproduced.

Number of bits used to store each value//

range of values/numbers/binary codes/binary patterns;

Sampling rate// frequency of sampling // time between samples/values;

What is meant by:

  • baud rate

the number of signal/voltage changes per second;

  • bit rate

number of bits per second / unit of time;

  • bandwidth

Range of frequencies a channel can handle;

  • The baud rate and the bit rate of a communication channel may be different. Explain
  • how this can occur.
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A signal can contain one or more bits;

Bit rate can be higher than baud rate;

bit rate = baud rate * number of bits per signal change;;

  • Procedures and functions are often self-contained. What is meant by the term
  • self-contained in this context?

Do not use any global variables// use only local variables and/or

parameters;

  • Give one reason why the use of global variables may introduce program bugs.

Local and global variables with the same name can be misidentified//

difficult to test individual procedures/ functions//

Not clear that as a side-effect of executing procedure/function a ...

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