Cromemco Z-2D - floppy disk woes & CP/M query - CP/M

This is a discussion on Cromemco Z-2D - floppy disk woes & CP/M query - CP/M ; Hi, I recently tested out a Cromemco Z-2D system which I was kindly given by a local company. This has a huge 21-slot motherboard, and I was slightly surprised to find just 4 boards (all Cromemco) - ZPU Z-80 board, ...

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Thread: Cromemco Z-2D - floppy disk woes & CP/M query

  1. Cromemco Z-2D - floppy disk woes & CP/M query

    Hi,

    I recently tested out a Cromemco Z-2D system which I was kindly given
    by a local company. This has a huge 21-slot motherboard, and I was
    slightly surprised to find just 4 boards (all Cromemco) - ZPU Z-80
    board, 4FDC floppy controller and serial console, 64KZ RAM board, and
    PRI parallel interface board. As the system hadn't been used in years I
    removed all the cards and powered it up gradually with a variac and
    series light bulb, thankfully everything was AOK. One slight concern is
    that the transformer is set for 220V and the UK is around 240V, so the
    S-100 voltages are nearly +8.8V and +17V rather than +8V and +16V, but
    the boards seem to work fine.

    Thanks to the wonderful collection of Cromemco manuals on the web
    (especially Daves Old Computers and S-100 manuals.com) I found the ZPU,
    4FDC,64KZ and RDOS manuals, and set the jumpers so that RDOS would
    start. After re-seating some chips and finding that the serial port
    connector needed a wiggle it now boots fine into the RDOS1 ROM (using a
    PC with TeraTerm as a terminal). I went through the pile of floppies
    that came with the system, and with the help of the RDOS commands:

    A;;; - to select A:
    S01 - to select track 1 etc

    I found that half the disks were formated OK (and I could read data
    off) and half weren't (I think these were for a Commoredore). I then
    tried booting the disks, and eventually found one that booted into CDOS
    2.36. I think this is based heavily on CP/M 1.3 from reading earlier
    posts.

    Now the problem I am having with the floppy drives (Tandon TM-100) is
    that the belts keep slipping off! This has happenned 3 times in the
    last hour so it is fairly unusable. I will try operating the system on
    its side (!) but the problem is the particular model of drive uses a
    flat drive pulley with no lip. I have some later Tandon TM-100-2s from
    the IBM XT and these have a lip on the pulley. I am reluctant to change
    the drives or even just the drive motors but I welcome any suggestions.

    Once the drives are sorted I will go through all the floppies, but I
    don't think they contain the CDOS INIT or other utilties to copy system
    disks. I've had a look at Dave's RT utility and will give that a go.

    Are there any archives of other CDOS software please?

    Finally are there any archives with CP/M for this set-up with 4FDC
    controller and 5.25" floppies?

    Thanks & regards,
    John


  2. Re: Cromemco Z-2D - floppy disk woes & CP/M query


    john.vc@btinternet.com wrote:
    ....
    > Now the problem I am having with the floppy drives (Tandon TM-100) is
    > that the belts keep slipping off! This has happenned 3 times in the
    > last hour so it is fairly unusable. I will try operating the system on
    > its side (!) but the problem is the particular model of drive uses a
    > flat drive pulley with no lip. I have some later Tandon TM-100-2s from
    > the IBM XT and these have a lip on the pulley. I am reluctant to change
    > the drives or even just the drive motors but I welcome any suggestions.


    You _did_ say _any_ suggestions...

    Something I learned many years ago while repairing a VCR.

    I cut a "replacement" from a bicycle tube. When stretched, it fit
    perfectly, and provided many years of service for my parents they let
    it start to collect dust. It would probably work today.


  3. Re: Cromemco Z-2D - floppy disk woes & CP/M query

    These are just standard 5.25" floppy drives. You can use any drives,
    even a half-height 360k PC drive. You may have to rejumper the drive to
    get a compatible configuration, but there is nothing special about the
    drives. [Well, I take that back on one account: the 4FDC requires a
    drive that has an on-drive one-shot data separator. Not all drives do,
    and even those that do are probably not jumpered to use it, since it was
    more common to feed unseparated clock and data to a data separator on
    the floppy disk controller. But the 4FDC has no data separator at all.
    The 16FDC, however, does.]

    I put a version of CP/M that will work with the Cromemco board set on
    the Harte web site. I think it's still there.


    john.vc@btinternet.com wrote:

    > Hi,
    >
    > I recently tested out a Cromemco Z-2D system which I was kindly given
    > by a local company. This has a huge 21-slot motherboard, and I was
    > slightly surprised to find just 4 boards (all Cromemco) - ZPU Z-80
    > board, 4FDC floppy controller and serial console, 64KZ RAM board, and
    > PRI parallel interface board. As the system hadn't been used in years I
    > removed all the cards and powered it up gradually with a variac and
    > series light bulb, thankfully everything was AOK. One slight concern is
    > that the transformer is set for 220V and the UK is around 240V, so the
    > S-100 voltages are nearly +8.8V and +17V rather than +8V and +16V, but
    > the boards seem to work fine.
    >
    > Thanks to the wonderful collection of Cromemco manuals on the web
    > (especially Daves Old Computers and S-100 manuals.com) I found the ZPU,
    > 4FDC,64KZ and RDOS manuals, and set the jumpers so that RDOS would
    > start. After re-seating some chips and finding that the serial port
    > connector needed a wiggle it now boots fine into the RDOS1 ROM (using a
    > PC with TeraTerm as a terminal). I went through the pile of floppies
    > that came with the system, and with the help of the RDOS commands:
    >
    > A;;; - to select A:
    > S01 - to select track 1 etc
    >
    > I found that half the disks were formated OK (and I could read data
    > off) and half weren't (I think these were for a Commoredore). I then
    > tried booting the disks, and eventually found one that booted into CDOS
    > 2.36. I think this is based heavily on CP/M 1.3 from reading earlier
    > posts.
    >
    > Now the problem I am having with the floppy drives (Tandon TM-100) is
    > that the belts keep slipping off! This has happenned 3 times in the
    > last hour so it is fairly unusable. I will try operating the system on
    > its side (!) but the problem is the particular model of drive uses a
    > flat drive pulley with no lip. I have some later Tandon TM-100-2s from
    > the IBM XT and these have a lip on the pulley. I am reluctant to change
    > the drives or even just the drive motors but I welcome any suggestions.
    >
    > Once the drives are sorted I will go through all the floppies, but I
    > don't think they contain the CDOS INIT or other utilties to copy system
    > disks. I've had a look at Dave's RT utility and will give that a go.
    >
    > Are there any archives of other CDOS software please?
    >
    > Finally are there any archives with CP/M for this set-up with 4FDC
    > controller and 5.25" floppies?
    >
    > Thanks & regards,
    > John
    >


  4. Re: Cromemco Z-2D - floppy disk woes & CP/M query

    On 25 Apr 2006 14:36:43 -0700, john.vc@btinternet.com wrote:
    >Hi,

    ....
    >S-100 voltages are nearly +8.8V and +17V rather than +8V and +16V, but
    >the boards seem to work fine.


    That's normal, the boards will cope with that.
    ....
    >Now the problem I am having with the floppy drives (Tandon TM-100) is
    >that the belts keep slipping off! This has happenned 3 times in the
    >last hour so it is fairly unusable. I will try operating the system on
    >its side (!) but the problem is the particular model of drive uses a
    >flat drive pulley with no lip. I have some later Tandon TM-100-2s from
    >the IBM XT and these have a lip on the pulley. I am reluctant to change
    >the drives or even just the drive motors but I welcome any suggestions.


    This was usually caused by slightly slack belts, these may have aged
    and loosened a bit. Normally having no lip on the pulleys was not a
    problem. You can try cleaning any grease off the pulleys and the belt
    - it sometimes works. I have used ex-IBMXT Tandon's with no problem on
    4-FDC and 16-FDC.

    >Once the drives are sorted I will go through all the floppies, but I
    >don't think they contain the CDOS INIT or other utilties to copy system
    >disks. I've had a look at Dave's RT utility and will give that a go.


    At the least you will want INIT, WRTSYS, XFER and CDOSGEN utils.
    Should be on the archives somewhere.

    Jim

  5. Re: Cromemco Z-2D - floppy disk woes & CP/M query

    I looked on
    http://www.s100-manuals.com/Harte-ma...mco/index.html (the
    Harte site?) but this has some CP/M files for 8" drive systems, I
    couldn't see any image files. Similarly on Daves Old Computers there
    are some 8" CP/M images (and possibly some 5.25" images for the 16FDC),
    I assume neither of these would work with a 4FDC and 5.25" drive
    set--up.

    Going back to the Tandon TM-100 drive belts, does anyone please know
    the specification for the belt? I have bought belts for my HP-85 from
    The Belt Corporation of America, just need the spec.

    Thanks for all the replies, this is a very useful forum.
    Regards,
    John


  6. Re: Cromemco Z-2D - floppy disk woes & CP/M query

    (note: don't reply to / email me at gmail.com. Read the end of this
    msg. - Herb)

    john.vc@btinternet.com wrote:
    > I looked on
    > http://www.s100-manuals.com/Harte-ma...mco/index.html (the
    > Harte site?) but this has some CP/M files for 8" drive systems, I
    > couldn't see any image files. Similarly on Daves Old Computers there
    > are some 8" CP/M images (and possibly some 5.25" images for the 16FDC),
    > I assume neither of these would work with a 4FDC and 5.25" drive
    > set--up.
    >
    > Going back to the Tandon TM-100 drive belts, does anyone please know
    > the specification for the belt? I have bought belts for my HP-85 from
    > The Belt Corporation of America, just need the spec.
    >
    > Thanks for all the replies, this is a very useful forum.
    > Regards,
    > John


    The 4FDC is the oldest of the Cromemco controllers. It has no data
    seperator circuit and as I recall will only work with single density
    5.25 or 8-inch formats.The manual for the 4FDC is of course
    informative. I don't recall if it includes a BIOS listing. Using
    another system you may be able to generate a CP/M disk, formatted
    appropriately from info you can glean from a FORMAT and BIOS listing,
    if you cannot get a boot diskette.

    You mentioned a company which offers drive belts. Please post specifics
    like address and Web site, etc. and some clues about price. Thank you.
    As for a specification, I don't believe Tandon likely specified it in
    any docs. You'll have to ask someone to measure their own belt. Sorry I
    don't have one handy to check.

    Herb Johnson

    Herbert R. Johnson, phone 609-771-1503, New Jersey USA
    web site
    domain mirror
    my email address: hjohnson AAT retrotechnology DOTT com
    if no reply, try in a few days: herbjohnson ATT comcast DOTT net
    "Herb's Stuff": old Mac, SGI, 8-inch floppy drives
    S-100 IMSAI Altair computers, docs, by "Dr. S-100"


  7. Re: Cromemco Z-2D - floppy disk woes & CP/M query

    Jim Attfield wrote:
    > >S-100 voltages are nearly +8.8V and +17V rather than +8V and +16V, but
    > >the boards seem to work fine.

    >
    > That's normal, the boards will cope with that.


    Thanks, yes thy are working fine.

    > >Now the problem I am having with the floppy drives (Tandon TM-100) is
    > >that the belts keep slipping off!

    > This was usually caused by slightly slack belts, these may have aged
    > and loosened a bit. Normally having no lip on the pulleys was not a
    > problem.


    On removing the drives and looking a bit closer, the drive pulley is
    convex which centres the belt when in use.

    Having re-fitted the belts and tighted up a loose pulley on one drive
    the belts are now staying put with use. However I am getting read
    errors on both drives and attempts to boot into CDOS are failing. The
    drives look in very good condition, I will try swapping the drives with
    some other Tandon drives from some other old computers (eg IBM) which
    work fine there, changing the jumpers as needed.

    > I have used ex-IBMXT Tandon's with no problem on
    > 4-FDC and 16-FDC.


    I understand the 16-FDC is later than the 4-FDC, and supports double
    density working. Does it generally work more reliablably too?

    > >Once the drives are sorted I will go through all the floppies, but I
    > >don't think they contain the CDOS INIT or other utilties to copy system
    > >disks. I've had a look at Dave's RT utility and will give that a go.

    >
    > At the least you will want INIT, WRTSYS, XFER and CDOSGEN utils.
    > Should be on the archives somewhere.


    Well, I've read the notes now on Dave Dunfields RT utility, and it
    clearly says it was tested on a 16-FDC system so I don't think it will
    work on my 4-FDC set-up. Back to searching for some disk images that
    will work on a 4-FDC, I haven't found one yet.

    Regards,
    John


  8. Re: Cromemco Z-2D - floppy disk woes & CP/M query

    On 1 May 2006 10:13:44 -0700, john.vc@btinternet.com wrote:
    >On removing the drives and looking a bit closer, the drive pulley is
    >convex which centres the belt when in use.
    >
    >Having re-fitted the belts and tighted up a loose pulley on one drive
    >the belts are now staying put with use. However I am getting read
    >errors on both drives and attempts to boot into CDOS are failing. The
    >drives look in very good condition, I will try swapping the drives with
    >some other Tandon drives from some other old computers (eg IBM) which
    >work fine there, changing the jumpers as needed.


    Watch out for the jumpers, IIRC it is different from PC jumpering and
    there is no cable twist on real PC's lol

    Only one resistor pack should be fitted at drive at physical cable
    end. Both motors start at motor on but obnly one head load light
    depending on drive selected.

    Grandmother, suck eggs, etc. Apologies if you already have this locked
    down - others may find it useful.

    >I understand the 16-FDC is later than the 4-FDC, and supports double
    >density working. Does it generally work more reliablably too?


    Assuming the on-board PLL clock for the data sep is adjusted properly
    the 16-FDC is fine but the 4-FDC was OK as well. Neither was a problem
    from reliability point of view. The 8" Persci's could be a bit twitchy
    but remarkable drives when on song.

    >Well, I've read the notes now on Dave Dunfields RT utility, and it
    >clearly says it was tested on a 16-FDC system so I don't think it will
    >work on my 4-FDC set-up. Back to searching for some disk images that
    >will work on a 4-FDC, I haven't found one yet.


    See what I can find in the odds'n'sods box lol I may have a 4-FDC or
    two lying around.

    Jim

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