Computer processing involves manipulating the symbols that represent things. It is the fastest and most accurate way of performing human tasks. The word ‘data’ is the plural of ‘datum’ means fact. It has three basic activities:
a) Capture Input data through input devices.
b) Manipulate by:
- organizing similar items into groups of alphabetic or alphanumeric codes
- Storing in logical order
- Summarizing in concise and usable form.
c) Managing output results by storing, retrieving, communicating and reproducing.
Need for Validation of Data: In addition to checking the correctness, data needs to be validated. This is performed during data preparation by visual review, logic validation tests etc. before it enters the processing run. It requires the logical capabilities of a computer program. Depending on how the application is designed, validation is performed during recording or conversion activities for early detection of errors.
Types of Validation Check = Check Digit: A check digit is determined by performing some arithmetic operations in such a way that typical errors are detected. Some methods are duplicating, echo check, validity check etc.
Input Validation: Before data is used, it is usually tested for errors. A separate input validation run or edit run may be used. It is performed on an input terminal. If errors are detected, it is shunted aside and written on an error file. Error logs are made to prevent duplicate corrections. Some validation checks are valid code, valid characters, valid field size etc.
Control and Security: The control over the quality of data processing should be established not just with a correct program but by a series of controls. Error detection and control procedures can be applied in data recording transmission, preparation, input, files and programs, output, distribution of output etc.
Need for Control of Access to Data Files, Procedures & Equipment: A data processing installation should establish and follow procedures to safeguard hardware, programs and data files from loss or destruction and in such an eventuality for reconstruction and recovery.
Access to the computer centre should be restricted to those having a need to be there. There must be special safeguards against access to computing resources and files. Some safeguards are use of ‘Lock Word’ or ‘Pass Word’, users catalog, scrambled data fields for confidential data etc.
Procedure Controls: In order to avoid or minimize destruction of data or programs, procedural controls can be used in Management. Some of these are external labels, magnetic tape file protection rings, Library procedures etc. Programs and files must be protected by copying and storing away from the premises. Any changes to program must be approved by program Manager or Processing Manager and a record kept. Program library management softwares are helpful.