If your “jobs” are waiting in queue, share time and physical resources.

Von Neumann’s architecture was the beginning of  the age of the modern computers, even though there were still many open issues.  Since 1955 the most of the calculators were  made by  transistors and the access to the physical resources in input and output ( punch cards, memory, magnetic tapes, prints) was faster. The typical calculators were the mainframes , systems for scientific and engineering computations. The computation process of them wasn’t very agile, both because of the several “jobs” in input (input data) and the long procedure to manage and produce the computation (output data). The output depended on the “jobs” in queue and the steps to get the result. Every job (the input datum on a punch card) was recorded on a magnetic tape of a mainframe (read phase), the tape was transferred to another mainframe with an OS (execution and computation phase), the tape with the results was moved again to the first mainframe for printing. These steps describe the batch processing. Too much hardware and too much time for processing the data. Kenneth Lane Thompson, a young researcher of AT&T Bell labs together with a staff of engineers, he was the first electrical engineer to design and create an OS (operating system) “time-sharing” and “multi-users”: it is UNIX.

Kenneth Lane Thompson

 It means the memory (RAM) allocates space for the OS and for the “jobs” (input data), the CPU (central process unit) is allocated in “time sharing” for every jobs and it is scheduled in asynchronous way.

“Time sharing” process

AT&T Bell labs begun to use some mini computers with UNIX for managing the telephone exchanges. Today UNIX  is one of the most famous OS in the world and it is used by the telecommunication companies for managing the network, the data and voice traffic. UNIX is totally written in C language which  is a standard for the telecommunication industry.