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An overview of operating systems, their history, roles, and importance. Discussions on the functions of an operating system, its evolution, and why it is essential to study. It also covers different roles of an operating system, such as a police state and a welfare state, and their techniques.
Typology: Slides
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n course information n schedule, assignments, grading and policy n other organization issues n see web pages for more information
n A program that acts as an intermediary between users and the hardware
n What tasks do we expect an OS to perform? n What needs to be part of an OS?
int array[SIZE];
main() { int sum = 0, i = 0;
while (i < count) { sum += array[f(i)]; i += g(i); } }
n When computers cost millions of $s, optimize for more efficient use of the hardware
n compile program input as punched card n load binary to some fixed location in memory n run for predefined duration, print results
n Next step enabled by: n Memory protection: prevent users from interfering with each other/OS n Relocation: load program at any memory location, execute
n Multiprogramming: several programs run at the same time
n Small jobs not delayed by large jobs n Overlap between I/O and CPU n OS requests I/O, goes back to a different job, waits for interrupt
n Bad news: OS must manage all these; each step logical, but gets complicated at some point
n Multics: announced in 1963, ran in 1969
n OS 360 released with 1000 bugs
n Unix based on Multics, but simplified to get it to work!
n Bell Labs was one of the players in Multics
n Ken Thompson was working on a “Space Travel” game program; ran on a GE 635 m/c at a cost of $75 in CPU time; started porting it to an unused PDP-7 in 1969 n Developed a small file system, ported the assembler, developed useful utilities (file copy, etc.) n Ritchie developed C language, Ken ported Unix to C n Developed shell, bunch of composable tools n Went to Berkeley, taught a course, and the rest is history
n Implementation details: n PDP-11/ n 16-bit word, 144KB of core memory n 1MB disk, four 2.5MB removable disks n Unix occupies: 42KB (“very large number of device drivers and enjoys a generous allotment of space for I/O buffers”)
Textbooks: Applied Operating System Concepts by SGG (recommended but not required)
Readings consist of:
n Technical papers (about 10-15; supplements class discussion: no reviews required) n Advanced papers (about 10-15): turn in reviews before lecture n Background readings
Official URL: http://zoo.cs.yale.edu/classes/cs
[http://lambda.cs.yale.edu/cs422]
For help, send email to instructor/TA.
n Unlimited processing power, infinite storage, single entity
n Tradeoffs between performance and functionality, division of labor between HW and SW
n Combine language, hardware, data structures, algorithms
“can I add some new functionality to an existing system?” “this system is so slow, can I do anything about it?”
n Threads and concurrency n Next two weeks n Virtual Memory n File Systems n Networks n Security
