Q&A-Data Processing


Differentiate between distributed data processing and time-sharing.

  • Distributed data processing is where computers located in physically separate location transmit data after processing to a server computer that updates the master file. Time-sharing on the other hand is where various terminals transmit data to be processed by a central computer's CPU. Each terminal's tasks are allocated a time slice of the CPU


During data entry, Anne typed the letter S instead of 5. What type of error is this?                                                                                                                                            (1mark)

        Misreading error


What is the difference between a logical file and a physical file?

  • A physical file contains the original data whereas a logical file does not contain any data
  • A physical file contains one record format while a logical file can contain up to 32 record formats
  • A physical file can exist without a logical file while a logical file cannot exist without a physical file


Distinguish between real-time and distributed operating systems (KCSE 2018)

  • Real-time OS reads information from input devices and must respond within a short duration of time to ensure correct performance
  • Distributed OS distributes computation among several physical processors which do not share memory or clock


Distinguish between real time processing and interactive processing

  • Real-time processing is where data is processed as it is received and the output is made available immediately to influence the ongoing activity
  • Interactive processing is computer processing in which the user can modify the operations appropriately while observing results at critical steps


Describe the difference between distributed and sequential processing on how they process instructions

  • Sequential processing occurs in the order that the tasks are received while distributed processing where more than one computer or CPU is used to run specific programs.


List Three file organisation methods in a computer

  • Sequential
  • Random
  • Serial
  • Indexed-sequential


State advantages of batch processing

  • once instructions are given, the processing runs automatically hence requiring little supervision
  • tasks are processed as a group hence reducing the cost
  • It is faster since the since runs automatically
  • there is increased output since the processor works without any interruption


State four threats that compromise data integrity and state ways that can be used to minimise these threats

State four threats that compromise data integrity

  • Human error
  • natural disaster
  • data transmission errors
  • software bugs

How threats to data integrity can be minimised:

  • Backup data preferably on an external storage media
  • control access to data by enforcing security measures
  • design user interfaces that minimise chances of invalid data entry
  • using error detection and correction software when transmitting data over the network
  • using devices that directly capture data from the source such as bar code readers, digtal cameras, and optical character readers



State what is meant by each of the following modes of data  processing

(i) Batch processing.
(ii) Real-time processing.
(iii) Online processing.
(iv) Off-line processing.

(i) Jobs collected together for processing at a later time
(ii) Output produced quickly enough to affect the next input
(iii) User has direct contact with the processor
(iv) User cannot communicate directly with the processor


Explain how the techniques of

(i) verification,
(ii) validation
are used to ensure that the stored data is as accurate as possible.

Dual input of data

  • Two inputs are compared by the system and any discrepancies are reported (and not stored.)
  • Data input once, either printed out or checked on the screen and  errors corrected

 Rules are given to the processor

  • Only accept A, B, C, D, E, F, G i.e Any other input rejected.

Drop-down list/radio buttons

  • Provides only valid inputs, so no other validation is required


When a new student is enrolled, a new record is added to the file immediately. The examination grades of all students are updated twice a year. Discuss the processing implications of these two requirements.

- Data input on line
- Individual records validated
- Speed mismatch implications
- Indexes updated immediately
Exam grades:
- Data input twice
- Off line
- Run as a batch
- At otherwise downtime


State two reasons why the data in fields such SEX field in a database should be coded.

  • less errors on input
  • requires less storage space
  • validation
  • quicker to input
  • quicker to find


 Lucy wrote: “I should validate the input into my database by typing in the same data twice”.Why was her statement incorrect?

  • she had actually described verification
  • data could be incorrect, therefore same incorrect data typed in twice
  • accept description of validation process e.g. range check


Distinguish between transcription and transposition types of errors and give an example of each  (4mks)

Transcription Errors: Transcription errors involve the incorrect entry of data due to mistakes made during the copying or typing process. These errors can occur when transferring information from one source to another.

Transposition Errors: Transposition errors specifically refer to errors where the order of characters or digits is accidentally reversed or swapped. This can happen during manual data entry or when processing information.