• There are several ways in which a computer, under the influences of an operating system is designed to process data.
• Examples of processing modes are:

1. online processing
2. real time processing
3. distributed processing
4. Time sharing
5. Batch processing
6. multiprocessing
7. multitasking
8. interactive processing

1. Online processing

• In online data processing data is processed immediately it is received. The computer is connected directly to the data input unit via a communication link. The data input may be a network terminal or online input devices attached to the computer.

1. Real-time processing

• Computer processes the incoming data as soon as it occurs, updates the transaction file and gives an immediate response that would affect the events as they happen.
• This is different from online in that for the latter an immediate response may not be required.
• The main purpose of a real-time processing is to provide accurate, up-to-date information hence better services based on a true (real) situation.
• An example of a real time processing is making a reservation for airline seats. A customer may request for an airline booking information through a remote terminal and the requested information will be given out within no time by the reservation system. If a booking is made, the system immediately updates the reservation file to avoid double booking and sends the response back to the customer immediately.

• Distributed data processing
• Multiprogramming, also referred to as multitasking refers to a type of processing where more than one program are executed apparently at the same time by a single central processing unit.Distributed data processing refers to dividing (distributing) processing tasks to two or more computer that are located on physically separate sites but connected by data transmission media.
  1. MultiprogrammingFor example, a distributed database will have different tables of the same database residing on separate computers and processed there as need arises.
     • This distribution of processing power increases efficiency and speed of processing. An example is in the banking industry where customers’ accounts are operated on servers in the branches but all the branch accounts can be administered centrally from the main server as if they resided on it. In this case, we say that the distributed database is transparent to the user because the distribution is hidden from the user’s point of view.
     1. Time sharing
     • In a time sharing processing, many terminals connected to a central computer are given access to the central processing unit apparently at the same time. However in actual sense, each user is allocated a time slice of the CPU in sequence. The amount of time allocated to each user is controlled by a multi-user operating system. If a user’s task is not completed during the allocated time slice, he/she is allocated another time slice later in a round robin
     1. Batch processing
     • Data is accumulated as a group (batch) over a specified period of time e.g. daily, weekly or monthly. The batch is then processed at once.
     • For example in payroll processing system, employees details concerning the number of hours worked, rate of pay, and other details are collected for a period of time say, one month. These details are then used to process the payment for the duration worked. Most printing systems use the batch processing to print documents.
     1. Multiprocessing
     • Refers to the processing of more than one task at the same time on different processors of the same computer. This is possible in computers such as mainframes and network servers.
     • In such systems a computer may contain more than one independent central processing unit which works together in a coordinated way.
     • At a given time, the processors may execute instructions from two or more different programs or from different parts of one program simultaneously.
     • This coordination is made possible by a multi-processing operating system that enables different processors to operate together and share the same memoryThe users of the distributed database will be completely unaware of the distribution and will interact with the database as if all of it was in their computer.