PDP-10 Incompatible Timesharing System emulator

by gattilorenz • 3 years ago

78 45 3 years ago

anthk2• 3 years ago

ITS it's the most amazing OS (with Emacs and "TV") you can try there.

Besides ITS proper, there were many subsystems that were more or less tied to ITS, some of them with their own operating systems. Others like the TV and XGP had dedicated PDP-11 computers running special software.

Just to list a bunch: PDP-6, Logo PDP-11/45, Minsky's 2500, Imlac PDS-1, GT40, Robotics PDP-11/40.

DonHopkins3• 3 years ago

From the offices at Tech Square, you could also call the elevator to your floor (by pressing Terminal-D), and buzz the elevator lobby door open from the comfort of your Lisp Machine (by pressing Terminal-E), via the PDP 10/11 interface on AI.

Random tourists could just pound on the door, and somebody would usually buzz you in without checking who it was, just to get some peace and quiet.

Lars, do you know anything about the wire wrapping robot that was on the 9th floor? Henry Minsky says he thinks either Holloway or Knight built it (Tom Knight would know), and they used it to make the CADR lisp machine boards. Those were huge freaking wire wrap planes, the size of a tabletop.

Here's Marvin Minsky demonstrating the 2500:

https://www.youtube.com/watch?v=c4kMzrDr4jQ

Cynthia Solomon's got a lot more amazing historic videos from that time:

Atari Cambridge Research- parts 1-6:

Introduction:

https://www.youtube.com/watch?v=CR2CwKculBU

Margaret Minsky demonstrates a gestural system:

https://www.youtube.com/watch?v=-Wq6SQTVM9M

It's 1984 and Ed Hardebeck shows a gestural system and Gary Drescher shows object-oriented Logo:

https://www.youtube.com/watch?v=ClKQHgIoLPc

A force feedback joystick, a puppet machine and a program of dance and body movement are presented:

https://www.youtube.com/watch?v=R3qPCZ5z0UQ

David Levitt shows the music box:

https://www.youtube.com/watch?v=ocwsVkqEKys

Music box with Tom Trobaugh and drum machine with Jim Davis:

https://www.youtube.com/watch?v=DhA0FGsin_s

zabzonk4• 3 years ago

Back in the 80s I moved from Queen Elizabeth College (part of University of London) which had just bought a couple of VAXen, which i thought were very smart, to Middlesex Polytechnic in north London who had a DecSystem10 running TOPS-10. It was horrible.We never ran ITS, maybe we should have.

rahen4• 3 years ago

And yet TOPS-10 was fairly advanced back in the sixties.

It is the common root of RT11, CP/M and PC-DOS / MS-DOS, but also one of the only system that allows to run batch and time sharing tasks at the same time. IBM couldn't do that, if you needed time sharing, you had the 360/67 but then you couldn't run batches.

Fun fact, Microsoft originally used a KA-10 running TOPS-10 and cross assemblers for software development. The PDP-10 was also a cornerstone of developing NCP/IP, TCP/IP, and early AI.

It's fairly hard nowadays to find 36 bits machines still running, as the 8 bits byte has taken over the world. I think XKL uses an FPGA-based PDP-10 running TOPS-20 on its TOAD2 router, but that's about all I'm aware of.

skissane2• 3 years ago

I think XKL uses an FPGA-based PDP-10 running TOPS-20 on its TOAD2 router, but that's about all I'm aware of.

I’m pretty sure the TOAD2 is a discontinued product. I believe their current routers run a BSD variant

https://news.ycombinator.com/item?id=30520851

zabzonk4• 3 years ago

And yet TOPS-10 was fairly advanced back in the sixties.

first release 1970, according to wikipedia.

It's fairly hard nowadays to find 36 bits machines still running,

true. one of our system programmers looked at buying our Dec10 but power supply and cooling problems defeated him - it was eventually sold for scrap.

ForOldHack• 3 years ago

Microsoft originally used a KA-10 running TOPS-10 and cross assemblers for software development - This was before they had Unix ported to their PDPs (Xenix)- and then Vaxes? Ms Piggy? Oh do tell! A lot happened between 1979, and 1984, when Xenix was released...

peebz• 3 years ago

I was at Middlesex Poly in the late 80s / early 90s doing an AI degree. I'm pretty sure one of the things we used was the EXSYS expert system shell running on VAX/VMS (because that's where I first came across the name). We didn't use it much though because the AI group had a bunch of early Macs that everyone preferred.

gumby2• 3 years ago

Such a great developer environment. The “shell” is a debugger.

larsbrinkhoff10• 3 years ago

It's hard to convey in words how convenient this is. Sometimes when you're debugging, you want to do file system things. In Unix you'd somehow switch out of the debugger to the shell (type ^Z or switch window, or something), do the thing, and then go back. With ITS you can just do it right away, and it somehow feels so right. Similarly, the debugger-shell has built-in math operators, so it can be your desktop calculator without switching context.

The system is wide open to a fault, even extending to the "kernel" memory image being available for debugging with just a few keystrokes.

gumby2• 3 years ago

It should be no surprise that the lispm had a similar experience. Instead of a shell it had a REPL of course but the debugger was always entered when something went wrong, and of course it was trivial to fix something and continue.

Bill Gates once laughed to my face when I described this as a feature.

msla• 3 years ago

This GitHub user account has a wealth of other PDP-10 stuff:

https://github.com/PDP-10

The Panda TOPS-20 distribution:

https://github.com/PDP-10/panda

TENEX, or TEN EXtended, the OS BBN made for the PDP-10s they extended to have paging virtual memory:

https://github.com/PDP-10/tenex

Muddle, the language Zork was originally written in:

https://github.com/PDP-10/muddle

Two different Zork codebases:

https://github.com/PDP-10/zork-1

https://github.com/PDP-10/zork

EdwardCoffin• 3 years ago

On the topic of ITS, there's a pretty interesting paper on its PCLSRing feature, PCLSRing: Keeping Process State Modular by Alan Bawden [1]

I've read this a few times over the years, and always find it a fascinating alternative approach to handling interrupts.

[1] http://fare.tunes.org/tmp/emergent/pclsr.htm

breput• 3 years ago

Oscar Vermeulen, the genius behind the PiDP-8[0] and PiDP-11[1] is making a PDP-10 scale model console[2], shown off recently at the Vintage Computer Festival SW[3][4].

[0] https://obsolescence.wixsite.com/obsolescence/pidp-8

[1] https://obsolescence.wixsite.com/obsolescence/pidp-11

[2] https://groups.google.com/g/pidp-10/c/Q_0LxSvOjaE

[3] https://groups.google.com/g/pidp-10/c/_1MjeJOz0AM

[4] https://photos.google.com/share/AF1QipP55SKT4c2F6wcAnIGV3goB...

WalterBright3• 3 years ago

You can run Empire on a PDP-10:

https://github.com/DigitalMars/Empire-for-PDP-10

larsbrinkhoff10• 3 years ago

In theory. As far as I know, attempts were made to resurrect this, but didn't get all the way there.

https://github.com/paulnank/nankervis-pdp10-js/issues/1#issu...

gattilorenz2• 3 years ago

Yeah, I was really looking forward to run the real SHRDLU [1] (one of the first natural language understanding programs) on ITS, but also that is... challenging. As you found out, it's possible to run a demo recording of it [2], and it's quite impressive too.

[1] https://en.wikipedia.org/wiki/SHRDLU

[2] https://github.com/PDP-10/its/issues/147

WalterBright3• 3 years ago

The way I debug such things is to start with a trivial FORTRAN-10 program, and get it to compile, link, and run. Then start adding pieces of Empire to it, and when it stops compiling and linking, then do a binary search on the code till the culprit is found.

larsbrinkhoff10• 3 years ago

Previously:

https://news.ycombinator.com/item?id=13514918

https://news.ycombinator.com/item?id=25869880

DonHopkins3• 3 years ago

ITS...

https://www.youtube.com/watch?v=i2s4tpqYrIg

larsbrinkhoff10• 3 years ago

Another fun tidbit related to this is that there were two prononciations of "ITS". The AI lab (where ITS originated) and the adjoining Project MAC slash LCS PDP-10s running ITS pronounced it as an acronym: "eye tee ess". But the Dynamic Modeling group (also in Project MAC), who were the first to adopt ITS outside the AI lab and had offices a few floors down, called it "its". I only learned about this recently when I talked to former DM people on video.

PDP-10 Incompatible Timesharing System emulator

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