Main Systems
Computer system physically shaped precursor big machine called mainframe systems. To run this system is done from a console. Input devices used in the form of card readers and tape drives. Output device used a line printer, tape drive and punch cards. Then, the user prepare a job that consists of programs, data and some control information (control card) and sent to a computer operator. Job is usually in the form of punch cards.
Some time later (in a matter of time minutes, hours or days), the output
displayed. Output of the results of the program, if an error occurs in the program memory and the register will contain a blank.
Operating system on the mainframe computer is very simple. Main Task send control automatically from one job to the next job. The operating system always resident in memory, called the resident monitor. Figure 1-2 is a picture memory layout in a simple batch system.
To increase the speed of the process, the same jobs that need to be collected together (batch) and executed by the computer as a group. Then programmer provides the program to the operator. The operator will sort the programs the same and then the computer will run each set of programs these. The output of each job is sent back to the programmer.
To avoid any CPUs that idle time long enough so developed a technique of working mengurutan job automatically. This technique is capable of automatically transfer control from one job to the next job. This form of system first operation. Small programs that are resident in memory contains sequences of jobs.