Information Technology - Revision Outline

Information Technology - GCSE Revision Outline © CPU

Syllabus (WJEC) Revision Outline IT Companion Course Notes Return

Read and learn from your worksheet notes.
Don't ignore anything you don't understand.
Make sure you have tried the sheets of practice questions.
Ask for help if you need to.
Short vague answers such as "It is quicker and more efficient" will not get marks. Always give reasons.
Describe and explain in detail. You are unlikely to run out of time, so write plenty.
See how many marks are available and try to make at least that number of different points.
Always give an example when you try to describe something, or draw a diagram.

For example, the following could be a 5-mark answer to the question "What is Batch Processing?"
(Note the use of a diagram, and terms like "eg ...", "... typical example ...", "... such as...", "... because ...")

Batch Processing means that a set of records has been entered (eg using key-to-disc input)
They might then be verified and sorted before being processed sequentially, one at a time starting from the first record until the end of the file.
Data from each record is added up to make a batch total which can be checked to make sure that every record in the batch has been processed correctly.
A typical example is merging a file of Sales transactions, captured using a method such Kimball tags, to update the Stock File, stored in order of stock code.
A system of backups is used (such as the Grandparent-Parent-Child system ) because errors in updating the Stock Records could lead to dissatisfied customers, incorrect re-ordering of stock, and false accounting.

Make sure you know which jobs might use the various input devices to a computer system:

keyboard, keypad, mouse, lightpen, grafpad, touch screen, scanner, video digitiser, voice recognition

Learn appropriate methods of data capture, and their advantages:

key-to-disc (including verification) for batch processing eg payrolls, mail-order
on-line keyboard input (validated by the program) eg travel agents enquiry system
no transcription (error-free, short queues) eg Barcode readers, Kimball tags, Document readers (OCR, MICR, Mark-sensing)

Consider the GIGO principle and learn examples of errors which can be trapped:

Verification: two typists enter the same data, which is then compared to spot any errors
Validation: when a program runs (eg Age= -900, Name="Fr4d", Date=32/13/1898);
Check digits

Make sure you know the terminology of databases:

Learn that a Record is a group of related facts about something (eg pupil records, stock records), and that each fact is known as a Field of data, and that a set of records is known as a File.
Fixed-length records can be accessed quicker, but Variable-length records save space.

Make sure you know the different methods of data access for finding records on a file:

Serial Access: starting from the first record and searching through one by one (Tape or Disc)
Direct Access: going directly to the record by calculating its address (Disc only)
Magnetic Tape: header record with file info, blocks of records, with inter-block gaps
Magnetic Disc: need to be formatted before use (magnetically organised into tracks & sectors)

Learn the purposes of different types of memory:

Main Store (RAM/ROM) - stores the programs and data being processed (fast, limited, expensive)
ROM is permanent (for " Boot" program); RAM is volatile (for programs & data during execution)
Backing Store (Floppy Disc, Hard Disc, Mag.Tape or Cartridge);
CD Rom for high capacity reference to text, video, sound (Multi-media).

Make sure you know the difference between the various methods of writing and running programs:

Assembler: translates low-level (mnemonic instructions, easier than machine-code, fast, compact)
Compiler: translates high-level program text into fast machine-code (eg Cobol, Pascal, Fortran)
Interpreter: executes one line at a time, easier to alter, but slow to run - (eg Basic, Logo)

Learn how an Operating System enables the computer to run programs and manage its resources:

Batch-processing runs a queue of programs, one at a time, non-interactively (eg Payroll)
Multi-programming runs until a peripheral transfer then switches programs so as not to waste time
Multi-access offers a time-slice to many interactive users (eg Theatre booking system)
Real-time gets results quickly enough to keep up with events as they happen (eg Steel production)

Learn the advantages of different types of computer output:

Character printers: dot-matrix (versatile), daisy-wheel (slow, quality text), ink-jet (quiet, versatile)
Line printers: (eg Barrel printer) expensive but very fast, text only (eg - A - A - A, BA - A - A, BANANA)
Laser printers: fast, photo-quality graphics
Digital Plotters: flat-bed plotter, drum plotter (large area, good graphics)
.... also vdu screen, sound generation, robot control
Computer Output on Microfiche (CoM) condensed output stored on transparent film:
ie output from computer (eg Customers’ Telephone BiIls) onto Mag.Tape, then photographically
reduced onto transparent film for safe compact storage, until lookcd at later in a Microfiche viewer.

Learn different Viewdata networks:

Teletext: non-interactive pages of information via television set
Prestel: interactive information, booking & buying, password protected for registered users
InterNet: world-wide web of information on any subject (text, graphics, sound, video)

Learn the benefits of Networks (eg LAN, WAN, Bus, Star, Ring):

sharing resources (eg printers, programs)
sharing information (electronic mail, tele-working, tele-conferencing)

If asked to design a data record, list the fields as if you were designing a database:

eg Fieldname Type Width Example

and if asked for a condition to search, use a filter or query:

eg CATEGORY equals "Fiction"AND AUTHOR contains "Agatha"

Learn as many different computer applications as possible:

Electronic office: wordprocessor, database, spreadsheet, electronic mail
Commercial: payroll, stock control, billing and invoicing, banking, theatre booking
Manufacturing: CAD/CAM, steel production, paper mills, car production
Construction: civil engineering (roads, bridges, dams, etc)
Control Systems: traffic light systems, security systems
Scientific: research, engineering design, modelling, statistics, CAL

Make sure you can discuss objectively the impact of computers on jobs:

jobs created: programmers, systems analysts, computer salespersons, computer agencies
jobs reduced: typists, filing clerks, payroll clerks, stock clerks, newspaper type-setters
jobs retrained: secretaries, librarians, journalists, engineers, draughtsmen

Learn the importance of data security and reliability

risk of customer disatisfaction, false accounting, false stock-keeping, dangerous mistakes
Verification, Validation, Check digits, Batch totals
Backups (eg grandparent-parent-child file security)
Passwords, Priorities, Read-Write access, Encryption (coded data)
Data Protection Act - personal information must be held securely; no longer than needed; no more information than needed; people may see their own data (by arrangement, at "reasonable" cost)
Hacking - unauthorised viewing can lead to theft, blackmail, espionage, dearer prices, lack of trust
Viruses affect the operating system when an "infected" disc is used, which then passes onto the next disc and thus spreads to other computers, to be triggered by a special event (eg April 1st)

Learn the jobs of DP personnel:

DP Manager, Systems Analyst, Programmers, Operations Manager, Control Clerks, Keyboard Operators, Media Librarian, Computer Operator, Maintenance Crew

Systems Analysis:

Investigation, Feasibility Report, System Design, Implementation & Testing

Make sure you understand the importance, in a new system, of Documentation and Training:
- Documentation: Installation requirements, Operating Instructions, Help/Tutorials, Trouble-shooting tips
- Training: Manuals, Courses, Videos , Pilot Scheme (ie a dummy run)
Top of page