CSa: UNIX and Multics
Multics – The First Seven Years – More of a classic retrospective paper (lots of . o Unix: Directories as special files (like indexes as relations). Multics is an influential early time-sharing operating system, based around the concept of a single-level memory. Virtually all. Story from the development of the Multics operating system. I said more, about the difference in goals of the systems, and about how much.
In Unix, the shell simply strips all newlines from the output of the called program if it is used for command output substitution. No other program needs to worry about the difference.
The Unix approach is much simpler, and also much less safe. The Multics approach ensures that the command makes sense, and the program being called expects to be called in that way. It prevents you from making insane calls. The Unix approach cuts out all the work required to make special forms of commands, and lets you do anything you want, even if it makes no sense and will likely screw up your login session.
The Multics approach is safe, but extremely limited. Many commands do not support active function use. About 80 multimillion-dollar sites were installed, at universities, industry, and government sites.
The French university system had several installations in the early s. After Honeywell stopped supporting Multics, users migrated to other systems like Unix. Salusauthor of a book covering Unix's early years stated one position: These averaged roughly lines of source code each, and compiled to produce a total of roughly 4.
Multics compilers generally optimised more for code density than CPU performance, for example using small sub-routines called operators for short standard code-sequences, making direct comparison of object code size with more modern systems less useful.
Unix and Multics
High code density was a good optimisation choice for a multi-user system with expensive main memory, such as Multics. Influence on other projects[ edit ] Unix[ edit ] The design and features of Multics greatly influenced the Unix operating system, which was originally written by two Multics programmers, Ken Thompson and Dennis Ritchie. Superficial influence of Multics on Unix is evident in many areas, including the naming of some commands. But the internal design philosophy was quite different, focusing on keeping the system small and simple, and so correcting some deficiencies of Multics because of its high resource demands on the limited computer hardware of the time.
The name Unix originally Unics is itself a pun on Multics. The U in Unix is rumored to stand for uniplexed as opposed to the multiplexed of Multics, further underscoring the designers' rejections of Multics' complexity in favor of a more straightforward and workable approach for smaller computers. Garfinkel and Abelson  cite an alternative origin: Peter Neumann at Bell Labs, watching a demonstration of the prototype, suggested the pun name UNICS — pronounced " eunuchs " — as a "castrated Multics", although Dennis Ritchie is said to have denied this.
It was close to unusable. They [Massachusetts Institute of Technology] still claim it's a monstrous success, but it just clearly wasn't. The Stratus VOS operating system of Stratus Computer now Stratus Technologies was very strongly influenced by Multics, and both its external user interface and internal structure bear many close resemblances to the older project.
The high-reliability, availability, and security features of Multics were extended in Stratus VOS to support a new line of fault tolerant computer systems supporting secure, reliable transaction processing. Stratus VOS is the most directly-related descendant of Multics still in active development and production usage today. There were little earphones for simultaneous translation at every seat.
After I gave my speech, there were questions from the audience. Someone asked a question in French, which was translated to me as, roughly, "You say that Multics has only 25 sites. There are already Unix sites. How does that make you feel? Afterward the local Multicians told me my questioner was one of an anti-Multics faction in Bull.
It occurs to me now that he was probably more likely pro-Unix than anti-Multics, but in those days there was a lot of fear and with-us-or-against-us thinking, and Multics was fighting for its life as usual.
Multics - Wikipedia
I don't think my answer satisfied either faction. When I finally got a chance to use Unix inon an Apollo workstation at Tandem, I felt instantly at home. The ls command, control arguments, shell scripts There were technical borrowings in both directions.