What is the history of operating system?

Answer 1

The history of computer operating systems recapitulates to a degree, the recent history of computer hardware. Operating systems (OSes) provide a set of functions needed and used by most application-programs on a computer, and the necessary linkages for the control and sychronization of the computer's hardware. On the first computers, without an operating system, every program needed the full hardware specification to run correctly and perform standard tasks, and its own drivers for peripheral devices like printers and card-readers. The growing complexity of hardware and application-programs eventually made operating systems a necessity.

Answer 2

Early computers lacked any form of operating system. The user had sole use of the machine and would arrive armed with program and data, often on punched paper and tape. The program would be loaded into the machine, and the machine would be set to work until the program completed or crashed. Programs could generally be debugged via a front panel using switches and lights. It is said that Alan Turing was a master of this on the early Manchester Mark I machine, and he was already deriving the primitive conception of an operating system from the principles of the Universal Turing machine.

Later machines came with libraries of support code, which would be linked to the user's program to assist in operations such as input and output. This was the genesis of the modern-day operating system. However, machines still ran a single job at a time; at Cambridge University in England the job queue was at one time a washing line from which tapes were hung with different colored clothes-pegs to indicate job-priority.

As machines became more powerful, the time needed for a run of a program diminished and the time to hand off the equipment became very large by comparison. Accounting for and paying for machine usage moved on from checking the wall clock to automatic logging by the computer. Run queues evolved from a literal queue of people at the door, to a heap of media on a jobs-waiting table, or batches of punch-cards stacked one on top of the other in the reader, until the machine itself was able to select and sequence which magnetic tape drives were online. Where program developers had originally had access to run their own jobs on the machine, they were supplanted by dedicated machine operators who looked after the well-being and maintenance of the machine and were less and less concerned with implementing tasks manually. When commercially available computer centers were faced with the implications of data lost through tampering or operational errors, equipment vendors were put under pressure to enhance the runtime libraries to prevent misuse of system resources. Automated monitoring was needed not just for CPU usage but for counting pages printed, cards punched, cards read, disk storage used and for signaling when operator intervention was required by jobs such as changing magnetic tapes.

All these features were building up towards the repertoire of a fully capable operating system. Eventually the runtime libraries became an amalgamated program that was started before the first customer job and could read in the customer job, control its execution, clean up after it, record its usage, and immediately go on to process the next job. Significantly, it became possible for programmers to use symbolic program-code instead of having to hand-encode binary images, once task-switching allowed a computer to perform translation of a program into binary form before running it. These resident background programs, capable of managing multistep processes, were often called monitors or monitor-programs before the term OS established itself.

An underlying program offering basic hardware-management, software-scheduling and resource-monitoring may seem a remote ancestor to the user-oriented OSes of the personal computing era. But there has been a shift in meaning. With the era of commercial computing, more and more "secondary" software was bundled in the OS package, leading eventually to the perception of an OS as a complete user-system with utilities, applications (such as text editors and file managers) and configuration tools, and having an integrated graphical user interface. The true descendant of the early operating systems is what is now called the "kernel". In technical and development circles the old restricted sense of an OS persists because of the continued active development of embedded operating systems for all kinds of devices with a data-processing component, from hand-held gadgets up to industrial robots and real-time control-systems, which do not run user-applications at the front-end. An embedded OS in a device today is not so far removed as one might think from its ancestor of the 1950s.

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