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The Origin Of The Shell
davecb writes: "Louis Pouzin, the inventor of datagrams, just contributed an
article
to Multicians.org on the creation of the first shell, "runcom,"
on CTSS and later Multics." Multicians is one of the coolest sites I've seen -- if you think the odd Atari 2600 is retro, look out. They also provided information on the Multics scheduler a little while ago.
It is a pretty good title, perhaps I'm just being a little too literal. It wouldn't be the first time. I still laugh when I remember his analogy of operating systems as car salesmen - the bit that was something like :
Linux Guy : Our free tank does 200 mph whilst never needing gas. When it breaks we will come to your house to fix it.
Joe consumer : Stay away from my house you freak.
There is a big difference between "hacking up a better Minix" and creating a Multics clone; in the latter case, there was considerable integration between:
- The kernel, providing file, computation, and security services.
- Programming Language.
- Unix and Linux represent "minimalist" systems in a number of senses, and it seems that many prominent Linux kernel hackers prefer "more minimal" text editors like Vi to the sorts of complex tools like TECO and Emacs.
There has periodically been talk on alt.os.multics of recreating Multics; the problem is that since it tightly integrated together custom hardware, complex kernel, and a pretty sophisticated user space, there's just plain a lot to replicate.Note that the memory model was substantially different from that of Unix. With Unix, you open files and filter data in and out, and allocate memory dynamically on demand, Multics unified this, so that rather than "opening a file," you would instead "initiate a segment," so that all files would essentially be memory mapped into the address spaces of all participating processes.
Furthermore, whilst the evils of segmentation as seen with the 64k pages on the original "IBM PC" give people the impression that segmentation is evil, Multics made pervasive use of it to keep chunks of memory distinct.
Note that some of the later Pentium CPUs included segmentation instructions likely based on Multics that could have been used to help do memory management "the Multics way;" the lack of such on RISC (Alpha, IA-64, PPC, MIPS, ...) architectures and the perpetual impending doom of IA-32 means that having memory management in Multics style on "modern" hardware may need to wait another 15 years...
Multics was coded in PL/1, and the fairly byzantine complexity of PL/1 provides both the merit that some operations may be much better optimized than C, and the demerit of being pretty complex.
I just don't think "C hackers" would build Multics.
The only way I'd see it being likely would be if some of the retired Multics creators that made some Silly-Valley and/or DotCom millions decided to sponsor a several-year-long project involving a staff of on the order of a dozen pretty elite developers to provide some sort of "legacy" to retrieve Multics from the dead.
If you're not part of the solution, you're part of the precipitate.
This is a good debunking of Neal Stephenson's "In the beginning was the command line". In the beginning there was no command line, and when someone invented it, it was as "revolutionary" as graphical user interfaces where when Douglas Englebart invented them. They are certainly not an intrinsic part of any computer as he seems to imply.
A better title would have been "In the beginning was the sheep". Sheep produce wool, so man invented the loom. Then Jacquard invented the programmable loom. Then Ada Lovelace wrote "punch cards" for it and thus was programming invented.
rc definition at FOLDOC. :)
I know which I'd rather put money on...
Well, well, well; three holes in the ground...
The 'rc' designation (as in /etc/rc.d/) comes from an abbreviation of 'runcom'.
-- Ed Avis ed@membled.com