Off Topic - PDP11/23

I am doing a little re-arranging of stuff in my basement, and I have to make a decision as to what do with my PDP11/23 system.

I have a 6.5' rack cabinet which holds the PDP11/23 box, a, I think, 5MB drive, and some other items. This stuff was purchased some 35 years ago, when I was ambitious, and I wanted to set up a "real" server, in my basement. Back thirty five years ago the system was in working condition, so I am making an assumption that if turn the system on, everything should still be working,

At that time I also purchased, P-sys OS, which came on the hard drive. The hard drive, for the curious. is about the size of a large microwave oven, and it weighs about 75 pounds, I think. Since there are a lot of old-timers here, my question, has anybody worked with P-sys OS? I do have the printed documentation for the OS, but I do not recall having a chance to work with the OS, back then. I wonder if it would be worth while to spend some time with the OS? Anybody have some thoughts about this.

Ray

Comments

  • frank freedmanfrank freedman Posts: 1,754
    edited 2020-11-08 - 03:44:38
    At the beginning of my time with Siemens, there were some imaging systems using DEC PDPs and later microVAx. (GE was big on Data General I think). I do remember that it was running VMS. Maybe consider keeping the front panel stuff and put a prop2 emulating a PDP and controlling the panel. For y'all watching the Tao a few days ago (hmmm, WWJMD) and if the grey cells are still correctly linked, the PDPs and VAX series actually used OCTAL!!!



    missing conditional....
  • Cluso99Cluso99 Posts: 16,943
    edited 2020-11-08 - 04:05:57
    Ray,
    Please post pic(s) ;)

    By the 80's single rack sized (or equivalent) mini-computers were common although big HDDs still maintained their own standalone position as washing machine sized boxes.

    First is my ICL System 25 (~1982 model) - under my desk around the middle with the multicoloured bag leaning against it.

    Next is a pair of ICL System 25's with HDD between them (56MB removable over 130MB fixed) at one of my customer's sites.

    And last, from my System Ten mini-computer from 1975 (purchased in 1977) - 4x Singer/ICL System Ten Model 40 10MB removable HDDs - under the cartons. They cost $16K each in 1975. The processor is out of view on the left, and it's twice the width and twice the height of the disc drives. Having my own computer allowed me to work from home and not having to get free time on Singer/ICL computers at 2-6am.

    980 x 735 - 178K
    816 x 612 - 150K
  • I guess I should have taken some pictures when the rack was populated. Since the the rack weighed in at over two hundred pounds and was top heavy, I took all the units out, so I could move the rack to another location.

    I am still not sure if I will be putting the components back in the rack, still floundering on that decision. Since I do have the rails for the rack, I wonder if a modern rack mount Dell server would fit in there.
    Maybe consider keeping the front panel stuff and put a prop2 emulating a PDP and controlling the panel.
    The unit that I have does not look like the old IMSAI box, with a bunch of toggle switches. The box basically has an on/off switch, now the back side is a different story, but that would be a bunch of ribbon cables and DB-25 cables hanging out.

    I will probably keep the cabinet, I am starting to like the idea of using the available rails. Just what I need, another major project :smile:

    Ray
  • I came across this explanation for P-sys:
    What is the UCSD P-System?
    It is a portable operating system that was popular in the early days of personal computers, in the late 1970s and early 1980s.

    Like today's Java, it was based on a "virtual machine" with a standard set of low-level, machine-language-like "p-code" instructions that were emulated on different hardware, including the 6502, the 8080, the Z-80, and the PDP-11. In this way, a Pascal compiler that emitted p-code executables could produce a program that could be run under the P-System on an Apple II, a Xerox 820, or a DEC PDP-11.

    The most popular language for the P-System was UCSD Pascal. In fact, the P-System operating system itself was written in UCSD Pascal, making the entire operating system relatively easy to port between platforms.

    By writing a p-code interpreter in the platform's native assembly language, and a few minimal hooks to operating system functions for the file system and interacting with the user, you could move a p-code executable from another system and run it on the new platform. In this way, the p-code generated on one computer could be used to bootstrap the port of the P-System to another computer.

    Interesting, did not know that you could write an OS with Pascal. Hmm, write an OS with Spin2, to bad we do not have a stronger P2 processor.

    Ray
  • Rsadeika wrote: »
    ..........

    I have a 6.5' rack cabinet which holds the PDP11/23 box, a, I think, 5MB drive, and some other items. This stuff was purchased some 35 years ago, when I was ambitious, and I wanted to set up a "real" server, in my basement. Back thirty five years ago the system was in working condition, so I am making an assumption that if turn the system on, everything should still be working,
    ........ Ray

    Electrolytic capacitors tend to fail when left unpowered for long periods of time so you may need to replace them.
    Rsadeika wrote: »
    I came across this explanation for P-sys:
    ..............................................
    Interesting, did not know that you could write an OS with Pascal. Hmm, write an OS with Spin2, to bad we do not have a stronger P2 processor.

    Ray

    You can write an OS in any language that can access the basic hardware of the processor, and the P2 has enough memory and more than enough processing power to write a reasonably powerful OS. It could run CPM, MPM, and even a WIMP os.
  • Cluso99Cluso99 Posts: 16,943
    edited 2020-11-08 - 21:11:23
    FWIW P1 and P2 both run CPM already. There is an OS for P1 and P2 too. The P2 code is not totally debugged tho.

    The System Ten mini (released 1970) had its’ disc based OS written in assembler. The max memory was 110KB (6bits actually) core memory. HDD was 10MB and up to 10 drives. Typical of the day was 20-40KB and 20MB. Full online real-time order entry, inventory control, and accounting were typical applications. All written in assembler. But this was no ordinary assembler - there were only 13 base assembler instructions in the first version.
  • And how much did such a machine cost?
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