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It will be a very, very rare person, OS hobbyist or not, who is willing to learn PL/1 just to be able to read the sources for MULTICS.

PL/I is hardly a difficult language to understand. It's similar to ALGOL in some respects, which eventually led to varieties of Pascal and Modula. Having some knowledge of data languages will help also, but once again, there isn't a whole lot that shouldn't be apparently to those who know C and SQL.

MULTICS was an interesting operating system but it always seemed buggy and unstable. Hopefully, the opening of the source code will help others avoid mistakes with a quick history lesson.

Have to agree there, anyone who is even remotely profficient in C should be able to read some PL/1 although it was heading in the Algol direction while C is more transparent to the hardware.

Also before C even arrived on micro computers, Intel had a subset of PM/1 that was probably as close to hardware as C was, it was part of their development systems they sold for 8085 and early 8086 boxes.


The only problem with reading really old software codes esp going way back to 50-60's codes is that the whole way of thinking about machines was in a different context. They were the first to do something or certain ways of doing things were common knowledge then and now forgotten. One has to set aside much of what one knows today to appreciate what was done then.

It's a nice idea, but a lot of the time earlier products are used as the basis, at least in part, to build newer products.

I'm sure Microsoft wont release the Windows 3.11 source code because there's still bits of it in Vista. ;-)

I'm sure Microsoft wont release the Windows 3.11 source code because there's still bits of it in Vista. ;-)

Forget that. There is still a crapload of DOS in Vista. Microsoft's operating systems just collect more cruft as they release newer versions. All because they are bent on supporting legacy software which, oddly enough, doesn't work very well most of the time.

He's serious!

Come on!!! it's no secret that Microsoft goes a long way (or so they say) to make sure that legacy applications run on Windows... I'd day MS programmers have to support APIs going back to MS-DOS 3.0... and we all know how good Microsoft Software is in general... so no wonder things fail anyway.

Well, they do that via a virtual machine environment which runs on top of the Win32 subsystem. So I wouldn't say that DOS is a critical or core component of Windows, by far. The NT kernel, in fact, has very little in common with DOS. The old-style APIs are only on the very surface of Win32 (the APIs exported by the core DLLs: kernel32.dll, gdi32.dll and user32.dll). All the other Windows APIs, such as those exported by ntdll.dll, the kernel and other newer components have very little win3.1 or DOS in them. Heck, even the old style Windows API calls aren't very DOS-y at all.

I can't tell if you're being sarcastic for humorous effect, or if you actually believe that...

Believe what? It's all true. Almost the entire DOS operating system is still in Vista. Look for yourself. You can still run "edit" and execute 16-bit executables. As far as compatiblity goes it's a nightmare for Vista. Financial software, antivirus programs, pre-2003 Office, various games, etc that have been designed for XP no longer work on Vista.

Edited 2007-11-13 22:53

We all know SCO invented MULTICS, and owns all patents on anything ever done with it.

... This brings up interesting question. The patents would, of course, be long since dead, but can you sue for infringement on your work for *past* infringement, even if it wouldn't be infringement *now*?

Edited 2007-11-12 19:27 UTC

Just hire lawyers like Civiletti, Miller, Sielbersky and soon you will have a case. You might not win but there is a possibillity. Those guys has pulled off the impossible before.

being as much of MULTICS is from BEFORE software patents were even allowed by the patent office, opening it up would be the prior art doom for a good chunk of the software industry. Many companies like IBM only started collecting patents in the 70's and 80's in earnest.. the original good stuff was long in public domain, but kept private because nobody release the source. A release like this would show how big a sham software patents really are.

Good point!

It may be that if some software developer is attacked by Microsoft or others for infringing a software patent, the developer may now be able to dig through the Multics code and prove that the technique or algorithm was in regular use BEFORE the patent was issued. This release may well protect some innocent people.

'tootsie pop'

-- is that a euphemism for something? Really, I have no idea what that's supposed to mean

Nope, it's a type of candy:

http://en.wikipedia.org/wiki/Tootsie_Pop

Good thinking right there....

Well, then shouldn't that be GNU/Multics? :-P

Seriously, though, hot plug and hot *unplug* memory in the 60's was a way cool feature that we are just catching up to today.

Yeah, I attempted to hotplug some DDR2-667 last week. The smoke effect from the motherboard was most realistic.

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"Yeah, I attempted to hotplug some DDR2-667 last week. The smoke effect from the motherboard was most realistic."

/dev/mem: Device disappeared
All processes exited on signal 11: Out of memory
Page fault, reload OC/EC

:-)

No - its demise was caused by the direct and concerted effort of Honeywell (who had acquired GE's computer business) to kill it because it was seen as a competitor of its own GCOS (GECOS back in the GE days) mainframe OS. GE, and later Honeywell, had built 600/6000 series mainframes with special hardware modifications specifically designed to support MULTICS.

Particularly in the Government space, MULTICS was very highly regarded and was the OS preferred by many. Honeywell almost lost a very large Government contract because they tried to push GCOS down a customer's throat when they really wanted and insisted on MULTICS.

As for performance, I never heard of any complaints regarding how MULTICS ran on the 6000 series mainframes - only kudos.

MULTICS was a true time-sharing OS. GCOS was a batch oriented OS with a timesharing subsystem (TSS) tacked on later and which became the rationalization used by Honeywell as to why MULTICS was no longer needed. Many, many customers mourned the demise of MULTICS, and Honeywell lost many customers when it died.

By the way, those who worked on MULTICS at Honeywell referred to themselves, and were referred to by others as Multicians. It is rumored that a number of these Multicians' feet did not touch the ground when they walked.

Edited 2007-11-12 22:18

Without history mankind is next to nothing.

yeah, a tar ball would have been nice.

as for the language, it is written in PL/I. It is one of the first OS's written in a high level language, instead of assembly.

I'm doing a mirror right now and prepare to do a tarball + torrent

i wonder what those go for on ebay these days

GCC can compile PL/1 code

I thought that was a joke, but to my surprise it's true: http://pl1gcc.sourceforge.net/

For all your information about Multics:

http://www.multicians.org/

In particular:

Multics ran on specialized expensive CPU hardware that provided a segmented, paged, ring-structured virtual memory. The system is a symmetric multiprocessor with shared physical and virtual memory. Standard Honeywell mainframe peripherals and memory were used.

(http://www.multicians.org/general.html)

Also: http://www.multicians.org/fjcc1.html

I remember reading once that a few megabytes (of 8-bit bytes) is enough, so most of the problems in emulating the hardware will be the CPU and MMU.

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