Revision Outline

• 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 …”)

1. Batch Processing means that a set of records has been entered (eg using key-to-disc input)
2. 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.
3. 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.
4. A typical example is merging a file of Sales transactions, captured using a method such as Kimball tags, to update the Stock File, stored in order of stock code.

5. 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.

1. 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

2. 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)

3. 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

4. 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.

5. 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)

6. 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).

7. 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)

8. Learn how an Operating System (OS) 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)

9. 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 looked at later in a Microfiche viewer.

10. 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)

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

> sharing resources (eg printers, programs)

> sharing information (electronic mail, tele-working, tele-conferencing)

12. 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”

13. 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

14. 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

15. 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)

16. Learn the jobs of DP personnel:

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

17. Systems Analysis:

> Investigation, Feasibility Report, System Design, Implementation & Testing

18. 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)