Different Types of Processing of CPU

A Central Processing Unit (CPU) process tons of data every day to make easy our like and every day job. In this page we will discuss about most important types of processing of CPU (Central Processing Unit).

Types of processing of CPU

Batch processing: Batch processing involves collecting transactions together over some interval of time and then processing the whole batch.

Batch systems allow automatic job sequencing by a memory resident monitor and improve the overall utilization of the computer.

The computer no longer had to wait for human operation. CPU utilization is still low, because of the slow speed of the I/O devices relative to the CPU.

Batch processing is used in banks for balancing checking accounts. A bank can make a record of all checks of the day and compute account balancing in a batch at the end of the day. This is one of the most important types of processing of CPU.

On-line processing: in on-line processing the computer and terminals act interactively. If the program allows the user to enter data or look at results before continuing with the next step it is sometimes known as conversational mode. Many computers use batch and on-line processing at the same time.

Spooling: Buffering is an approach to improve system performance by overlapping the input, output, and computation of a single job. Spooling allows the CPU to overlap the input of one job with the computation and output of other jobs.


(a) On-line and (b) Off-line operation of I/0 devices



Spooling also provides a pool of jobs which have been read and are waiting to the run. This pool of jobs supports the concept of multiprogramming.

With multiprogramming, several jobs are kept in memory at one time; the CPU is switched back and forth between them in order to increase CPU utilization and to decrease the total time needed for the execution of a job.


Memory layout for multiprogramming

Multiprogramming: Multiprogramming was developed to improve performance of computer systems. It also allows time sharing.

Time-shared operating systems allow many users (up to several hundred) to use a computer system interactively at the same time.

Time sharing system: A time-sharing operating system allows many users to share the computer simultaneously. Since each Acton or command in a time-shared system tends to be short, only a short CUP time is needed for each user.

As the system swathes rapidly from one user to the next, users are given the impression that each user works on a separate computer while actually one compute is shared among the users.


Real-time and time-shared systems

Real-time systems: Another form of operating system is the real-time system. A real-the system is often used as a control device in a dedicated application. Transducers and sensors bring data to the computer.

The computer must analyze the data possibly adjust controls to sensor inputs. Systems which control scientific Experiments, medical systems, industrial control systems, and some display systems are the examples of real-time systems.

Virtual Memory: The size and sophistication of a program is limited by the amount of main memory available. The virtual memory technique uses some rapidly accessible secondary memory to augment main memory.

Portions of programs are swapped into main memory from virtual memory (also called virtual storage) as  needed. This give an illusion that Main memory is available than actually these cases. Virtual memory is usually implemented by  segmentation or paging or a c combination of them.

Segmentation is the process of dividing a program into segments of different sizes and placing the segments in memory wherever they fit. Paging is similar to segmentation except that programs are divided into equal sized portions.

As with segmentation, the operating system keeps tracks of page locations by constructing page table. As page are of fixed size, the use of paging results in less wastage of real storage space.

The best memory management scheme is to combine segmentation and paging by first segmenting programs and then further subdividing each segment into pages.

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