Rose Quote:

If only.... "In the late 1960s, Bell Labs was involved in a project with MIT and General Electric to develop a time-sharing system, called Multiplexed Information and Computing Service (Multics), allowing multiple users to access a mainframe simultaneously. Dissatisfied with the project's progress, Bell Labs management ultimately withdrew. On the PDP-7, in 1969, a team of Bell Labs researchers led by Thompson and Ritchie, including Rudd Canaday, implemented a hierarchical file system, the concepts of computer processes and device files, a command-line interpreter, and some small utility programs, modeled on the corresponding features in Multics, but simplified. The resulting system, much smaller and simpler than Multics, was to become Unix." Even in beginning it was supposed to be multiuser system, kinda hard without multitasking...

Multics was an innovative but underachieving OS for large expensive mainframe computers designed to support time sharing. The Bell Labs guys did not try to create a replacement for Multics but rather were more interested in downsizing a similar OS while retaining and improving on some of the concepts. The PDP-7 and later PDP-11 minicomputer hardware was lower end than a mainframe and very resource limited. One of the motivations was to play the game "Space Travel" which cost $75 per session on a GE mainframe. Unix was primitive on the PDP-7 while the PDP-11, which inspired the 68k, opened up new possibilities for both Unix and what became the C language. Unix development started in 1969 on the PDP-7 but it was not until 1973 on the PDP-11 when multitasking was implemented.

Dennis Ritchie Quote:

Thus, in 1971, work began on what was to become the C language. The story of the language developments from BCPL through B to C is told elsewhere, and need not be repeated here. Perhaps the most important watershed occurred during 1973, when the operating system kernel was rewritten in C. It was at this point that the system assumed its modern form; the most far-reaching change was the introduction of multi-programming. There were few externally visible changes, but the internal structure of the system became much more rational and general. The success of this effort convinced us that C was useful as a nearly universal tool for systems programming, instead of just a toy for simple applications.

https://web.archive.org/web/20170403063715/https://www.bell-labs.com/usr/dmr/www/hist.pdf

"Multi-programming" is running more than one program at a time and implies multitasking. Time sharing also implies multitasking but Unix was originally developed on hardware which made it difficult to implement. There may have been multiuser concepts in the file system of Unix from inception like "protection modes" but I guess the users had to take turns using the OS. AmigaOS file systems often support both user and group protection bits while full multiuser support was never implemented. At least the AmigaOS was designed to be minimal and support preemptive multitasking from inception. The AmigaOS started with the superior 68000 which is practically a 32 bit super PDP-11. Both Unix and the AmigaOS designs made compromises to be usable on more affordable hardware, at least partially motivated by computer gaming.

More Amiga Unix parallels are legal disputes over IP and lawsuits for many years. The end result for Unix was that the free reimplementation called Linux became the most successful branch and many of the Unix businesses involved in the legal disputes disappeared. This would be like AROS becoming the dominant AmigaOS branch and Hyperion, A-Eon and AmigaKit disappearing. Some new Amiga hardware is already including AROS.

https://en.wikipedia.org/wiki/History_of_Unix

Sorry for the thread interruption but clarification was needed. If a more in depth discussion is desired then please start a new thread.

Last edited by matthey on 02-Feb-2022 at 05:24 PM.