TYPES OF PROCESSING MODES

Data must be processed by the most suitable means.  It can then be transferred to one or more computer systems for further processing, output or storage. Processing can be achieved by three methods:

1. Batch processing – data is collected in a batch before processing starts.  With early computers, data was entered on ‘punched cards’ (or Hollerith Cards), which were handled in batches, hence the term batch processing.  Most suitable for tasks where a large amount of data has to be processed on a regular basis.  When a batch job begins, it will continue until it is completed or until an error occurs.  Examples of batch processing include those that process utility bills such as water and electricity, payroll systems and examination report cards.

Advantages

• Once the data is submitted, the computer can be left to run without human interaction
• The computer is only used for a certain period of time for the batch job
• Jobs can be scheduled for a time when the computer is not busy 

Disadvantages

• There is always a delay before the work is processed because batch jobs are stored over a period of time
• Involves the use of an expensive computer and a large number of trained staff

2. On-line processing – computers and peripherals devices are ‘on-line’ when they are connected to a main processor and powered on, so that the operator can interact with them.  Examples of on-line processing include devices such as printers which are on-line when they are ready to receive data from the computer to print.  Most printers have an on-line button you can press to turn the machine on.  If it is turned off, then you are off-line.  You can also be on-line if you are connected to the Internet through a modem or network.

3. Real-time processing – real-time processing systems process data without significant delay, making it always up-to-date.  Since processing must be connected to one or more computers to process data, then it must also be on-line. (N.B. on-line systems do not necessarily imply that processing is real-time since there may be delays with an on-line system).  Examples include aeroplane landing control system, flight simulation, electronic fund transfer systems and ticket reservation systems.

Advantages

• No significant delay for response
• Information is always up-to-date
• Output from the computer may be used to adjust and improve the input back into the system

Disadvantages

• The computer must be dedicated solely to the task
• The computer must always be on-line