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Thread: Today: a ND-100/CX Compact computer

  1. #11
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    I tested the drive with a PSU (ATX) today. As soon as the PSU is powered up, the drive spins up. It spins for a while (maybe a minute or two), then stops. It does this every time. Any hints?
    And BTW, the drive is ST-506, not SCSI.
    Micropolis 1325 specs here: http://stason.org/TULARC/pc/hard-dri...MFM-ST506.html
    but they don't say anything about motor behavior.
    Last edited by tingo; October 21st, 2011 at 01:58 PM. Reason: added ST-506 confirmation. Added Micropolis 1325 data link.
    Torfinn

  2. #12
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    Talking Fixing a Micropolis (ST-506) drive

    From a discussion on the cc-tech mailing list, I got a description on how to fix the "sticky bumper" problem on a Micropolis ST-506 drive. These drives have rubber "bumpers" as end-stops for the drive head. And after many years this rubber becomes sticky, resulting in the head not having enough power to "unstick" itself from the bumper when powered up.

    The solution is (for me at least) quite scary: open up the drive, move the head and put a piece of paper between the rubber "bumper" and the head part. Then all will be well (if the drive doesn't have other problems).

    So I did. First I had set up everything I needed: a psu to test the drive with, some post-it paper, screwdriver, scissors, a small flashlight.
    The top cover has ten screws, and six of them is partly or totally obscured by the label. I simply peeled away the label above the screws.
    After unscrewing, I used a small flat-blade screwdriver to loosen the cover; the gasket made it stick to the housing. Then I lifted the top cover carefully off (on the inside, the airflow duct is connected to it), and started to look for the bumpers.
    Since I haven't seen the inside of one of these drives before, it took a while before I realized that the "bumpers" where inside the head assembly; there is only two small slits where you can see them when you move the head. There is also a locking mechanism that prevents the head from moving freely if the drive isn't powered on.

    When I moved the head assembly with my fingers, there was very little resistance; I started thinking that maybe there was something else wrong with this drive.

    But I cut a small strip of post-it paper (maybe 2 or 3 mm wide), moved the head a bit and put it into the hole between the head and the bumper that the head rested on when turned off. Simply releasing the head made the paper stick to the bumper.

    Testing; I powered up the drive (yes, with the cover off) and now the head moved out when the drive had finished spinning up. Before the paper, the head hadn't moved at all. Aha!
    It was the "sticky bumper" problem after all. I re-assembled the drive, powered it on, and let it be on for about four minutes. Success!
    Torfinn

  3. #13
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    Wink Testing the machine

    After fixing the drive; I had to test if it worked.
    I put it back in the machine, connected it up, and powered up the machine. I waited maybe a minute or two, but nothing happened, so I pressed the "START" button.
    Almost immediately, the "RUNNING" light on the panel turned on. This hadn't happened before!

    After a few more minutes, I got this on the console (transcribed):
    Code:
    BATCH NUMBER =  1
    13.14.12     15 SEPTEMBER 1987
    SINTRAN III - VSX / 500 K  ******** VÄLKOMMEN TILL DEMO SIMULATORN ********
    STANDARD CONFIGURATION: C
    GENERATION (WORK MODE NO.):  312B
    REVISION (PATCH FILE NO.): 11400B
    CPU TYPE: 102
    CPU NUMBER: 3608
    GENERATED: 13.14.00     15 SEPTEMBER 1987
    SINTRAN III RUNNING -
    
    PAGES FOR SWAPPING: 1357B
    
    ND-100 PANEL CLOCK INCORRECT
    
    1987.09.15  13:14:21 ** XROUT: xmsg  version L03 (87.11.26) started **
    
    *** 13.14.40 TERMINAL 670:
    ***INFORMATIONS SIMULATORN ÄR NU FÄRDIG ATT ANVÄNDA ***
    Yes! The machine is working again!
    Pressing ESCape got me the "ENTER" prompt, and I could log in as user SYSTEM (without password):
    Code:
    OK
    SIM-INFO..@
    Happy now.
    Torfinn

  4. #14

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    Awesome! It looked the same the few times it worked for me!

    Also, I don't think I gave you the systems history. I got it from a university which ran a big ND-500 to control a simulator for of a small Nuclear Reactor. The simulator was quite neat, complete with control room and everything. The software on the ND-500 had been ported to a GNU/Linux system. So the ND-500 was donated to a friend of mine and later made it's way to another collector in Sweden. The ND-100 was sitting next to the 500 and according to the donor had never been used for as long as he could remember. However, I suspect it is somehow related.

    Congratulations on getting it going again!
    Looking for: anything from SGI or DEC/digital
    Pictures of my collection: www.pdp8.se

  5. #15
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    Quote Originally Posted by pontus View Post
    Also, I don't think I gave you the systems history. I got it from a university which ran a big ND-500 to control a simulator for of a small Nuclear Reactor. The simulator was quite neat, complete with control room and everything. The software on the ND-500 had been ported to a GNU/Linux system. So the ND-500 was donated to a friend of mine and later made it's way to another collector in Sweden. The ND-100 was sitting next to the 500 and according to the donor had never been used for as long as he could remember. However, I suspect it is somehow related.
    This is very interesting. Do you know if there is any information available on this simulator?

    Quote Originally Posted by pontus
    Congratulations on getting it going again!
    Thanks. It was a really satisfying moment.
    Torfinn

  6. #16
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    I wonder how they transferred data to and from this machine?
    - it has TCP/IP software installed, but not Ethernet card (and no cabinet wiring or connectors on the back plate for that either)
    - the only terminal is the console; not other terminal interface cards in the machine (again: no wiring and no connectors for that on the back plate)
    - there are no other communication cards (HDLC, Megalink or others) in the machine

    But the TCP/IP software is configured with a list of systems to talk to...
    Torfinn

  7. #17
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    It sounds like there must have been an Ethernet interface card in the machine at some point. The ND-100 we had at work had an Ethernet card and that was the main form of connection (well, the first years we had a bunch of terminal card interfaces in the machine and we wired current loop to all offices). Admittedly there was more room in our non-compact-model ND-100, but there's room in the crate of your machine for more cards than it currently has, no?

    -Tor

  8. #18
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    Yes, there is plenty of space in the card crate:
    1. 3033 - PCB 3033 ND100 CPU, Print: S, Eco: V
    2. 3104 - PCB 3104 ND100 Mem. Man. II, Print: G, Eco: N
    3. (empty)
    4. (empty)
    5. 3041 - PCB 3041 ST506 Disk Contr. Print: E, Eco: K
    6. 3112 - PCB 3112 8" + 5 1/4" fl. + str., Print: B, Eco: J
    7. 3009 - PCB 3009C Local I/O Bus, B-interface address 151X
    8. (empty)
    9. (empty)
    10. (empty)
    11. (empty)
    12. 3042 - PCB 3042 ND100 2 Mby RAM, Print: B, Eco: C



    But I am puzzled by the lack of wiring; I can unsderstand that they used the cards elsewhere; but the wiring?
    Torfinn

  9. #19
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    Quote Originally Posted by tingo View Post
    This is very interesting. Do you know if there is any information available on this simulator?
    I found this document (PDF). I don't know if it is the correct one, but it has interesting information about the Compact Simulators:
    the first so-called Compact Simulators were build in Studsvik in the early 1980s.
    ...The old system used a so called minicomputer
    of the Nord 500/100 type, a two-CPU system with a size of about two large
    refrigerators. A four meter long operator’s panel was connected to the Nord
    computer. An external computer terminal was used to communicate with the
    Nord system. The system featured five large CRT colour screens, controlled
    from the Nord computer, via a display system based on a microprocessor and a
    several graphical electronics cards under the panel.
    and about the software:
    The present software is built around a condensate of the old Fortran code from
    the Nord system. All the main physical processes in the reactor simulation
    uses the old code, modified in order to run on a GNU/Linux system on the
    x86 architecture. The Fortran modules are built into a framework of C-code,
    handling the general control of the software, including timing, a graphical user
    interface, and a display system for the five LCD screen on the operator panel. A
    dedicated kernel driver written in C that controls the communication between
    the parallel port of the PC and the external interface card is loaded into the
    Linux kernel at system startup.
    The Fortran modules responsible for the different parts of the reactor plant
    use a total of between 6500 and 7000 process parameters (variables and con-
    stants). These are shared between the modules by a number of large COMMON-
    blocks defined in Fortran.
    Very interesting.
    Torfinn

  10. #20

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    I don't know much about the simulator. But the PDF you found is definitely related. How do I know that? Well, the physical description is spot on, I know the fellow who ported the software to GNU/Linux and I know the simulator was used for teaching students about nuclear physics.

    Also, If you'd like a network card or other parts I could get you in touch with Göran in Umeå. He is the mother lode of ND in Sweden
    Looking for: anything from SGI or DEC/digital
    Pictures of my collection: www.pdp8.se

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