Programs are the instructions telling the computer how each type of transaction is to be processed. These instructions include routines of checking & controlling data matching data with master files and performing mathematical operations on the data, e.g. for a sales transactions. Matching routines will enable the computer to identify the right sales price from the sales price master file and the right customer from debtors master file, mathematical routines include calculating the total debtors amount and updating customer’s balance on the debtors’ master file.

Operating Systems

Relate to a series of related programs to provide instructions as to what files are required to be on-line, what output devices are required to be ready and what additional files need to be created for further processing e.g. with a batch of sales transactions, the sales price file and the debtors file need to be on-line. The printer must be loaded with blank invoice forms and the totals must be retained for posting to the sales and debtors control accounts in the general ledger master file.

An operating system will also provide details of further processing runs within the same system. So, for example, in sales these will include updating the general ledger, processing cash receipts andcredit notes to the debtors file, printing out monthly statements and printing out an analysis of due accounts for credit control purposes.

In a batch processing system, the operating system may consist of a set of instructions provided to the operator but increasingly the operating system is part of the computer software such that with real time system, the computer identifies source of an incoming signal, and automatically processes that transaction using the appropriate programs and the right file.


Each system should be fully documented. This documentation should include:

i. The initial specification, objectives and authorisation of the system.

ii. Overall flowchart of the flow of information through the system including the manual procedures.

iii. An indication on the flowchart of the programs and files involved in the system.

iv. For files, the contents of each file and the way the data is stored within the file.

v. For programs, a logic flowchart as well as complex details.

vi. Copies of input and output documents.

vii. Operator instructions including error messages.

viii. Data used in testing the system and the results.

ix. Changes in the system and any of the component parts and the authorisation of the changes.