all of sani

The compatible time-sharing system(ctss) system( corbato et al.(1962) was designed at MIT as an experimental time- sharing system. It was implemented on an IBM 7090 and eventully supported up to 32 interactive users. The users were provided with a set of interactive commands that allowed them to manipulate files and to compile and run programs through a terminal.
The 7090 had a 32kb memory, made up of 36-bit words. The monitor used 5kb words, leaving 27kb for the users. User memory images were swapped between memory and a fast drum. CPU scheduling employed a multilevel- feedback-queue alogorithm. The time quantum for level i was 2* i time units if a program did not finish its CPU burst in one time quantam, it was moved down to the next level of the queue, giving it twice as much time . the program at the highest level(with the shortest quantum) was run first. The intial level
of program was determined by its size, so that the time quantum was at least as long as the swap time.
CTSS was extremly successful and was uses as late as 1972. although it was limited, it succesded in demonstrating that time sharing was a convenient and practical mode of computing. One result of CTSS was increased devlopment of time-sharing systems. Another result was the devlopment of MULTICS.