Form 3


Data procesing refers to the transformating raw data into meaningful output.

Data can be done manually using a pen and paper, mechanically using simple devices eg typewritter or electronically using modern dat processing toolseg computers

Stages of the data processing cycle.

Data collection involves getting the data/facts needed for processing from the point of its origin to the computer

Data Input- the collected data is converted into machine-readable form by an input device, and send into the machine.

Processing is the transformation of the input data to a more meaningful form (information) in the CPU

Output is the production of the required information, which may be input in future.

The difference between data collection and data capture.

Data capture is the process of obtaining data in a computer-sensible form for at the point of origin (the source document itself is prepared in a machine-sensible form for input)

Data collection involves getting the original data to the ‘processing centre’, transcribing it, converting it from one medium to another, and finally getting it into the computer.

The 5 stages of data collection.

Data creation

Data transmission

Data preparation

Media conversion (i.e, conversion of data from one medium to another

Input validation


Relevance of the term garbage in garbage out (GIGO) in reference to errors in data processing.

The accuracy of the data entered in the computer directly determines the accuracy of the information given out.

Give and explain two transcription and two computational errors committed during data processing.

Misreading errors: -they occur when the user reads source document incorrectly, thus entering wrong values, e.g. a user may confuse 5 in the number 586 with S, and type S86 instead.

Transposition errors: - they result from incorrect arrangement of characters (i.e., putting characters in the wrong order especially when keying data onto a diskette), e.g. the user may enter 396 instead of 369 computational errors

Overflow errors: -An overflow occurs if the result from a calculation is too large to fit in the allocated memory space, e.g., if the allocated memory space is able to store an 8-bit character, then an overflow will occur if the result of the calculation gives a 9-bit number.

  • Underflow
  • Truncation: 0.784969 784
  • Rounding error:30.6666 7
  • Algorithm or ,logical errors

Data integrity.

Data integrity refers to the dependability, timeliness, availability, relevance, accuracy & completeness of data/information

Ways of minimizing threats to data integrity.

  • Backing up the data on external storage media
  • Enforcing security measures to control access to data
  • Using error detection & correction software when transmitting data
  • Designing user interfaces that minimize chances of invalid data being entered.

Briefly explain real-time processing.

  • Airline reservation systems
  • Theatre (cinema) booking
  • Hotel reservations
  • Banking systems
  • Police enquiry systems
  • Chemical processing plants
  • Hospitals to monitor the progress of a patient
  • Missile control systems

Advantages and disadvantages of

Real-time system.


  • Provides up-to-date information
  • The information is readily available for instant decision-making
  • Provides better services to users/customers.
  • Fast &reliable
  • Reduces circulation of hardcopies.


  • Require complex Os & are very expensive
  • Not easy to develop
  • Real time systems usually use 2 or more processors to share the workloads, which is expensive.
  • Require large communication equipment.

The Differentiate between CPU bound jobs and I/O bound jobs.

CPU bound jobs require more of the CPU time to process these jobs. Most of the work the I/O devices perform is on the Input; and Output; hence, they require very little CPU time.

Most companies are now shifting from the use of geographically distributed personal computers. This method of data processing is known as Distributed Data Processing (DDP)

Three computing resources that can be distributed.

-CPU (Processors) time


-Application software


-Computer processing power

-Memory (computer storage)

- Input/Output devices, e.g. printers

-communication devices/communication port

Examples of industries and business organizations that extensively use distributed processing systems.

  • Banks
  • Computerized retails stores, e.g. supermarkets
  • Learning institutions with many departmental offices
  • Bureaus or communication cyber cafes
  • Airline reservation systems

Benefits and three risks that might be associated with the distributed data Processing system.

The load on the host computer is greatly reduced

  • The use of low cost minicomputers minimizes the cost in data processing
  • Delays in data processing are reduced
  • Provides better services to the customers
  • There is less risk in case of system breakdown
  • The design & implementation of the system is less complex due to decentralization
  • The level of expertise required is less.


    • Data duplication is very common
    • Programming problems occur with microcomputers & minicomputers
    • Security threats, i.e. the data & information sent one the network from one place to
    • another can be tapped, or listened to by unauthorized parties
    • More training is needed for the users involved
    • It is expensive due to the extra cost of communication equipment.

The concept of multi-programming

A Multi-programming system allows the user to run 2 or more programs, all of which are in the computer’s main memory, at the same time.

Benefits that are derived from multi-programming

  • It increases productivity of a computer
  • Reduces the CPU’s idle time
  • Reduces the incidence of peripheral bound operation

Advantages of storing data in computer files over the manual filing system

  • Stored information takes up less space
  • Easier to update and modify
  • Provides faster access and retrieval of data
  • Reduces duplication of data or stored records
  • Cheaper
  • Enhances data integrity (i.e. accuracy and completeness)

The difference between logical and physical computer files.

A logical file is viewed in terms of what data items it contains and what processing operations may be performed on the data

A physical file is viewed in terms of how the data items found in a file are arranged on the storage media and how they can be processed.

Arrange the following components of the information system data hierarchy in ascending order of complexity:

Field, Database, Byte, Record, Bit, and file

Bit Byte Field Record File Database

Types of computer processing files

i) Report file- It contains a set of relatively permanent records extracted from the data in a master file.

They are used to prepare reports, which can ve printed at a later date, e.g. report on student’s class performance in the term, extract of students who have not cleared their school fees, report on absentees
ii) Backup file- Used to backup data or to hold duplicate copies of data/information from the computer’s fixed storage or main file for security purposes e.g. a copy of all the students admitted in a school fees, report on absentees

iii) Reference file - Used for reference purposes. It contains records that are fairly permanent or semi-permanent, e.g. Deductions in caution money, wage rates, tax deductions, employees address, price lists etc.

iv) Sort file – used to sort/rank data according to a given order, e.g. ranking position in a class of students.
v) Transaction file - Is used to hold input data during transaction processing. It is later used to update master files and audits daily, weekly or monthly transaction.


What is file organization?

  1. It is the way records are arranged (laid out) within a particular file or any secondary storage device in a computer
  2. Refers to the way data is stored in a file
  3. File organization is important because it determines the method of access, efficiency, flexibility and storage devices to be used.

Methods of file organizatio

Sequential and serial

In sequential file organization, records are stored in a sorted order using a

key field, while in serial; the records are stored in the order they come into the file, and are not sorted in any way.

Random and indexed-sequential

In random file organization, records are stored in the file randomly and accessed directly, while in indexed –sequential, the records are stored sequentially but accessed directly using an index.

Serial file organization

Records are in a file are stored and accessed one after another on a storage medium

Indexed sequencial file organization method

Similar to sequential method, only that an index is used to enable the computer to locate individual records on the storage media.

ELECTRONIC DATA PROCESSING MODES käyttää vain välttämättömiä evästeitä istunnon ylläpitämiseen ja anonyymiin tekniseen tilastointiin. ei koskaan käytä evästeitä markkinointiin tai kerää yksilöityjä tilastoja. Lisää tietoa evästeistä