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Thread: I just bricked a lovely Mostek STD-Bus / MDX boards Development System

  1. #1

    Default I just bricked a lovely Mostek STD-Bus / MDX boards Development System

    I bought this wonderful system off Craigslist a few weeks ago from someone who worked at Mostek in the early 80s as a product manager. He was given this machine which he listed as a "Mostek Development System".

    It is a prototype that was made by Mostek around 1984 (or 1983) as they were trying to get a foothold in the microcomputer (complete) systems market I believe.

    It uses the STD-Bus, a variant of the S-100 bus, and has 5 Mostek MDX cards installed on a backplane: CPU3 (Z80), RAM (128 K), FLP2 (floppy controller), SASI (hard disk controller), and an SIO card (serial input/output). This is driven by a 250 w power supply. There is a 10 MB hard disk (Miniscribe III) and a 5.25" DD, DS floppy drive installed in the custom made case (the owner said the case alone must have cost Mostek about $500 to get custom made back in the 80s - its super durable and well made). CP/M 3.0 was installed on the hard disk, and the system booted off the hard disk reliably.

    The floppy controller was configured to drive an 8" drive, which was also included in the sale. This was external to the main unit and connected to one of the ports in the back. Lots of 8" floppies were included, including one entitled "CP/M 3.0 SYSGEN".

    Also included was an ADDS terminal and keyboard. What an awesome system, I was so psyched to get it.

    So... now the awful part.

    I don't know much about CP/M to begin with, but even less about version 3.0. For some unknown (and ridiculously stupid) reason, I was messing around with the .COM files in the main root directory just to see what the programs did, thinking they couldn't do any actual damage without some prompt like "are you sure you want to do this?"

    So long story short, I ran a program called GENCPM, and quickly ran through a series of prompts about floppy disk parameters and some other (probably critical) settings. The program exited with an error, saying it couldn't write to some file I believe.

    The next time I booted the machine (and ever since), the CP/M Loader starts up and then hangs with the error message "can't read file CPM3.SYS"

    So I've learned a LOT about CP/M 3 in the days since I made this ridiculous and horrendous mistake. It turns out I ran the utility that generates a new CPM3.SYS file, which is the customized version of CP/M for a specific hardware setup, and mine ended on an error. What a mess. This is truly a low point in my retro computing career.

    Any help or ideas would be greatly appreciated.

    IMG_1163.JPG

  2. #2

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    Yes, it does seem that CPM3.SYS was destroyed by your running GENCPM. I assume that is on the harddisk? If you have a bootable floppy, you may be able to restore it. Typically, that vintage of harddisk system has some method to recover from a crashed drive, which is similar in result to what you experienced. Look for floppies labeled "recovery" or such. Even if it is CP/M 2.2, it may be enough to re-run GENCPM (choose the correct answers this time) or possibly locate another copy of CPM3.SYS. Also, look for a file GENCPM.DAT which might contain the correct values to use - unless your run overwrote it.
    - Doug

  3. #3

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    Google fot Colex 820 or Colex 850, which is an almost identical STDBUS cp/m system

  4. #4

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    Thank you for the feedback, honestly. I most likely destroyed the CPM3.SYS
    file (which is basically the operating system), but I have some hope that
    all the other files and system structure is still maintained on the hard
    disk, especially since the boot loader (CPMLDR) is at least starting up.

    So yes, CPM3.SYS and CPMLDR.COM are both on the hard disk. I don't have any
    5.25" or 8" floppies with recovery media, except the 8" drive labeled
    "CP/M 3 GENSYS", which may have a back up copy of CPM3.SYS. Or maybe there
    is a backup right on the hard disk, renamed to something else.

    If I could somehow boot the machine with a minimal operating system, I could
    then find out for sure what is on there. Thank you jdreesen for pointing
    me to the Colex 820, it does in fact look very close to this system! Does it
    matter that my system is using MDX boards by Mostek? It seems like a slightly
    different technology than the standard STD-Z80-BUS cards, but maybe I'm
    wrong. I will look for system disks (CP/M) for the Colex, that may be my
    saving grace if I can get it on an MFM formatted 5.25" floppy and get the
    floppy drive set up on the Mostek computer's floppy controller.

    Thanks also Doug for the helpful suggestions of how to hopefully rebuild
    things once I can get in there.

    What a terrible, careless mistake I've made. Lesson learned. I seem to always
    run into trouble working on CP/M machines because they were a bit before my
    time. I grew up with DOS machines and give me any PC-compatible hardware and
    I can throw a system together without fail.

    Here's more detail on the machine I have:

    250 w power supply
    STD-Z80-Bus passive backplane (?) with 10 slots
    Miniscribe III hard disk drive (10 MB)
    Mitsubishi M4854 5.25" floppy drive (double density, double sided?)
    Installed Mostek MDX cards:
    MDX-SIO (connects to J3 and J5 ports in the back)
    MDX-CPU3 (from Mostek 1983, a Z80 CPU on-board (MK3880N-4))
    MDX-RAM (128 K ram installed in two rows of 64 K)
    MDX-FLP2 (floppy controller)
    MDX-SASI-1 (hard disk controller)
    Qume Qumetrak 242 external 8" floppy drive

    The way it was set up when I got it:

    The hard disk booted CP/M 3 and became the A: and B: drives
    (each 5 mb)

    The 5.25" floppy was drive E: but was unresponsive because the
    MDX-FLP2 controller can only be set to support 8" or 5.25"
    drives, but not both at the same time.

    The 8" floppy was drive F: and I could read disks from it and
    I successfully formatted a blank disk with it.

  5. #5
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    I have a Colex 850 CP/M 3 boot disk; has all the files on it, including CPM3.SYS and GENCPM, etc. It's 5.25' 96 tpi DS. If you'd like to give it a try, I can post an .IMD file of it.

  6. #6

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    Quote Originally Posted by dvanaria View Post
    Does it
    matter that my system is using MDX boards by Mostek?

    AFAIK the Mostek and Colex boards are identical. My Colex 850 also is in need of repair.

  7. #7

    Default

    Quote Originally Posted by Chuck(G) View Post
    I have a Colex 850 CP/M 3 boot disk; has all the files on it, including CPM3.SYS and GENCPM, etc. It's 5.25' 96 tpi DS. If you'd like to give it a try, I can post an .IMD file of it.
    That would be awesome, thanks Chuck. I think you've helped me out on several other projects in the past.

    If I had the .IMD file, I would then use ImageDisk on a DOS machine (I have a 386 with a 360K floppy drive) to write the image, correct? Is there any particular version of ImageDisk you recommend, I think the latest is 1.18

    Thanks very much.
    Last edited by dvanaria; November 26th, 2019 at 07:36 PM.

  8. #8
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    No, you'll need a 1.2M or 720K drive--these are 96 tpi. 1.18 IMD is fine.

    Check your PMs--I sent a link to you.
    Last edited by Chuck(G); November 26th, 2019 at 08:41 PM.

  9. #9

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    I would say that before doing too much more, you might want to image the hard drive. Some setups when writing to the disk, write new data on an empty part of the disk while leaving the original data intact. Others just immediately write over the old data. The more you write to the hard drive, the less likely you are to find any of the original data. Imaging the drive is maybe the most important thing you want to do when you think there might be something there. CP/M uses a relatively simple directory structure.
    Dwight

  10. #10
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    Here is a Directory Listing for Chuck's Image:
    Code:
    cpmls -f clx2 -D COLEX850.RAW
         Name    Bytes   Recs  Attr     update             create
    ------------ ------ ------ ---- -----------------  -----------------
    CCP     .COM     4K     25 R  
    COPYSYS .COM     2K     15 R  
    COPYSYS .PRN    32K    249    
    CPM3    .SYS    20K    154 R  
    DATE    .COM     4K     22 R  
    DEVICE  .COM     8K     58 R  
    DIR     .COM    16K    114 R  
    DUMP    .COM     2K      8 R  
    ED      .COM    10K     73 R  
    ERASE   .COM     4K     29 R  
    FORMAT  .COM     4K     19 R  
    GENCOM  .COM    16K    116 R  
    GET     .COM     8K     51 R  
    HELP    .COM     8K     56 R  
    HELP    .HLP    62K    488 R  
    HEXCOM  .COM     2K      9 R  
    INITDIR .COM    32K    250 R  
    INSTALL .SUB     2K      1 R  
    LIB     .COM     8K     56 R  
    LINK    .COM    16K    123 R  
    MAC     .COM    12K     92 R  
    PARK    .COM     2K     16 R  
    PATCH   .COM     4K     19 R  
    PHASE2  .SUB     2K      1 R  
    PHASE3  .SUB     2K      1 R  
    PHASE4  .SUB     2K      1 R  
    PHASE5  .SUB     2K      1 R  
    PHASE6  .SUB     2K      1 R  
    PHASE7  .SUB     2K      2 R  
    PIP     .COM    10K     68 R  
    PUT     .COM     8K     55 R  
    PUTCPM3 .COM     8K     64 R  
    RENAME  .COM     4K     23 R  
    RMAC    .COM    14K    106 R  
    SAVE    .COM     2K     14 R  
    SET     .COM    12K     81 R  
    SETDEF  .COM     4K     32 R  
    SHOW    .COM    10K     66 R  
    SID     .COM     8K     62 R  
    SUBMIT  .COM     6K     42 R  
    TYPE    .COM     4K     24 R  
    WCPM3   .SYS    20K    154 R  
    WFORMAT .COM    12K     85 R  
    WRTSYS  .COM     2K     10    
    XREF    .COM    16K    121 R  
    XYZ     .SYS    16K    122    
    
    User 6:
    
         Name    Bytes   Recs  Attr     update             create
    ------------ ------ ------ ---- -----------------  -----------------
    ASMBIOS .SUB     2K      2    
    AUTO    .SUB     2K      1    
    BAUDRATE.MAC     2K      8 R  
    BOOT    .ASM     4K     29    
    BOOT5   .ASM     6K     35    
    BOOTPROM.MAC    16K    114    
    BOOTW   .ASM     6K     47    
    CBIOS   .ASM    20K    151    
    CHARIO  .ASM    16K    123    
    COPYRIGH.ASM     2K     12    
    COPYRIGH.MAC     2K     12    
    CPM3    .LIB     4K     32    
    CREF    .SUB     2K      1    
    DRVTBL  .ASM     2K      4    
    EQUATES .LIB     2K      2    
    FDRVTBL .ASM     2K      4    
    FLOPEQU .MAC     2K     10    
    FLOPPY  .ASM    32K    243    
    GENCPM  .DAT     4K     19    
    HDISK   .ASM    14K    106    
    LDRBIOS .ASM    20K    157    
    LINK820 .SUB     2K      1    
    LINK850 .SUB     2K      1    
    MODEBAUD.LIB     2K      8    
    MOVE    .ASM     4K     20    
    PORTS   .LIB     2K      7    
    SASIEQU .MAC     2K     11    
    SCB     .ASM     4K     19    
    Z80     .LIB     6K     47    
    
    User 12:
    
         Name    Bytes   Recs  Attr     update             create
    ------------ ------ ------ ---- -----------------  -----------------
    BOOT    .ASM     4K     29    
    BOOT5   .ASM     6K     35    
    BOOTW   .ASM     6K     47    
    CBIOS   .ASM    20K    151    
    CHARIO  .ASM    16K    123    
    COPYRIGH.ASM     2K     12    
    DRVTBL  .ASM     2K      4    
    EQUATES .LIB     2K      2    
    FDRVTBL .ASM     2K      4    
    FLOPPY  .ASM    32K    243    
    HDISK   .ASM    14K    106    
    LDRBIOS .ASM    20K    157    
    MODEBAUD.LIB     2K      8    
    MOVE    .ASM     4K     20    
    PORTS   .LIB     2K      7    
    SCB     .ASM     4K     19    
    Z80     .LIB     6K     47    
       92 Files occupying    396K,       0K Free.
    Thanks.

    Larry

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