Image Map Image Map
Page 1 of 4 1234 LastLast
Results 1 to 10 of 37

Thread: Docs needed for TRS -80 Model II Disk System

  1. #1
    Join Date
    Feb 2015
    Location
    Cleveland, OH, USA
    Posts
    1,168

    Default Docs needed for TRS -80 Model II Disk System

    Having just acquired the above-mentioned disk system, complete with cable and two drives, I am now faced with figuring out what is in it, how it operates, what can be connected to it and what to look for before I power it up.

    Documentation, as it is commonly known.

    Anyone with information or practical experience willing to offer advice or guidance will be greatly appreciated.

    Thanks,

    -CH-

  2. #2
    Join Date
    Dec 2009
    Location
    Kelowna, BC, Canada
    Posts
    24

    Default

    (Peter Cetinski will almost certainly answer this, but I'll try to save him the time)

    Peter Cetinski has a Model II archive at:

    https://github.com/pski/model2archive

    You can find the documentation you are looking for in the hardware directory:

    https://github.com/pski/model2archiv...aster/Hardware

    Specifically, you can find the documentation for the disk system here:

    https://github.com/pski/model2archiv...ion_System.pdf

    - Rick

  3. #3
    Join Date
    Feb 2015
    Location
    Cleveland, OH, USA
    Posts
    1,168

    Default

    Thank you for this information. After reading the DS documentation I have a couple more questions:

    Do you know who sourced the drives? I read somewhere that they were CalComp.
    Do you know whether the disks (Catalog 26-4905) are hard or soft-sectored?
    Can the system be interfaced with any of the other TRS-80 machines, e.g. Model III, 4, 12 or 16?

    Thanks again,

    -CH-

  4. #4
    Join Date
    Dec 2009
    Location
    Kelowna, BC, Canada
    Posts
    24

    Default

    > Do you know who sourced the drives? I read somewhere that they were CalComp.

    Peter has some information on the drives here:

    https://pski.net/trs-80-model-ii-family/

    > Do you know whether the disks (Catalog 26-4905) are hard or soft-sectored?

    They are soft-sectored.

    > Can the system be interfaced with any of the other TRS-80 machines, e.g. Model III, 4, 12 or 16?

    Any of those machines should be able to connect to a Model II via a serial port and a terminal program (the Model III's serial port was an add-on, if I remember correctly, the rest had serial ports built-in).

    - Rick

  5. #5
    Join Date
    Feb 2015
    Location
    Cleveland, OH, USA
    Posts
    1,168

    Default

    Quote Originally Posted by Rick Thornquist View Post
    > Do you know who sourced the drives? I read somewhere that they were CalComp.

    Peter has some information on the drives here:

    https://pski.net/trs-80-model-ii-family/

    > Do you know whether the disks (Catalog 26-4905) are hard or soft-sectored?

    They are soft-sectored.

    > Can the system be interfaced with any of the other TRS-80 machines, e.g. Model III, 4, 12 or 16?

    Any of those machines should be able to connect to a Model II via a serial port and a terminal program (the Model III's serial port was an add-on, if I remember correctly, the rest had serial ports built-in).

    - Rick
    Once again, thank you for this information.

    Control Data supplied some of the expansion bay's drives, according to Peter's info:

    "Tandy offered a disk expansion system which allowed up to 3 additional 8 inch floppy disk drives to be attached to the system. The expansion bay was outfitted with full-height Control Data Corporation (CDC) disk drives until late in the Model II run. As in the the computer itself, TPI drives replaced the CDC drives late in the Model II lifetime."

    Shugart 800s were inside the Model II console, apparently.

    Soft-sectored is good news, so is Shugart.

    I regret that I wasn't more clear in my earlier question about interfacing: The expansion system has a 2x25 female connector at the end of a ~4-foot ribbon cable which undoubtedly connects to a Model II FDC. I am wondering if the Model II FDC was identical to any of those used in the other machines, or if an adapter, either passive or active, enabled the other machines to communicate with these drives in the expansion bay.

    I have a Model III and IV; I don't yet have a II, 12 or 16. So the ability, or inability, to interface with any of these machines is a subject of interest.

    Thanks again for your help.

    -CH-

  6. #6
    Join Date
    Dec 2009
    Location
    Kelowna, BC, Canada
    Posts
    24

    Default

    Gotcha.

    I haven't tried interfacing the thing to a III or 4, so I can't help you there. However, I have connected it to a FDC on a Pentium PC. It's not a direct plug-in deal, though. The 8 inch disks require a separate signal that 5 1/4 inch controllers don't provide. It's called TG43 and it indicates whether the drive is on a track greater than 43. There is an interface that can handle this, the FDADAP, but I think it's for PC FDCs only (I don't know the III or 4 FDCs, so I don't know whether it would work with them). In my setup, it goes between the 50 pin cable that comes out of the expansion bay and a 34 pin cable that comes from the FDC on the PC.

    This isn't exactly what you're looking for, but it might bump you in the right direction.

    Here's more info on the FDADAP:

    http://www.dbit.com/fdadap.html

    - Rick
    Last edited by Rick Thornquist; March 15th, 2020 at 02:04 PM.

  7. #7
    Join Date
    Dec 2009
    Location
    Kelowna, BC, Canada
    Posts
    24

    Default

    Oh, and about the 12 and 16...

    I actually don't know if the disk system will connect to the 12 or 16. There was a different disk system that attached to those machines that used double-sided drives (26-4165 and 26-4166). The Model II and the disk system used single-sided drives (26-4160, etc).

    This is actually a good question. Does anyone know if a Model II disk expansion system will work with a 12 or 16? Peter?

    - Rick

  8. #8
    Join Date
    Feb 2015
    Location
    Cleveland, OH, USA
    Posts
    1,168

    Default

    Thanks for your reply.

    I recently began a project to rebuild a Shugart 850 and in support of that began acquiring materials; among them, an FDADAP from http://www.dbit.com/fdadap.html . I expect I'll be able to use it when communicating with the Disk System, with a PC or the Device Side Data FC 5025 http://www.deviceside.com/ sending the control signals.

    I'm sort of following in the tracks of a lot of others on this site who have traveled this path in the past. The Shugart is my first venture into 8-inch territory and is unproven at this point but I have learned a lot from the experience.

    Unfortunately that means asking a lot of basic questions.
    Thanks for your help.

    -CH-

  9. #9
    Join Date
    Jun 2018
    Location
    Pacific NW in the islands
    Posts
    183

    Default

    there were two 8Ē drive makes used inboard to the model II: shugart and texas peripherials. all the model IIís were manufactured with shugarts, but some tpi went in as repair parts.

    the TPI drives were clones of the shugart sa800. texas peripherals was owned by tandy/rs. they are equivalent practically speaking. single sided/soft sectored as rick said.

    if youíre asking if you can use a model 3 or 4 fdc card with the model II, the answer is no. the model II technical reference manual is a very good overview. be aware that the schematics in there are early production. itíll explain a lot for you.

    the cdc drives in the external bay are notorious. tpi is much better and you will also see some shugarts in those bays. we treated shugart and tpi as equivalents for service purposes, though an attempt was made to swap like for like. if you have a bay with cdc drives, pay attention to the door close switch and pushrod assembly. iím not going to say it was junk, but iím thinking it.

    the sa800 is an easy drive to work on and is a solid drive.

  10. #10
    Join Date
    Feb 2015
    Location
    Cleveland, OH, USA
    Posts
    1,168

    Default

    Quote Originally Posted by shank View Post
    there were two 8” drive makes used inboard to the model II: shugart and texas peripherials.
    I have seen 5.25" drives in some RS equipment (the Model 100 "DVI") labeled "TEC". Is that the same company with a different brand or another supplier?


    Quote Originally Posted by shank View Post
    if you have a bay with cdc drives, pay attention to the door close switch and pushrod assembly. i’m not going to say it was junk, but i’m thinking it.
    As in: Press "up" (left) on the release at the "top" of the drive and the lower front drops "down" (swings right)? Hmmm....

    All good information, thank you for your response.

    -CH-

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •