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Thread: Replacing 8" drive with 3.5"

  1. #1

    Default Replacing 8" drive with 3.5"

    Can anyone help?

    My system is a SD SBC200 with Versafloppy2 floppy disk controller. It also has a Vector Graphic flashwriterII board for video output, and a Expandoram 2 card. With a Vector Graphic monitor ROM installed I can run this machine via the flashwriterII card with output to a composite monitor, or with the SD monitor ROM installed I can run the machine via serial to a terminal. Both setups access a single Gotek flashfloppy drive. The same Gotek disk images run CP/M 22 on both setups.

    What I have been trying to to do is set up a 3.5" drive as Drive B. I have a Teac 235HF that has been modified to spin at 360rpm.

    CP/M can see the drive as Drive B, and I am able to run a format utility and the drive seems to format and steps through it's tracks...unfortunately I can not access the drive after the format and I get a BDOS error.

    I should mention that this setup is very similar to my IMSAI 8080. A Gotek + modified Teac 235HF 3.5 drive, although the Teac drive is setup as drive A. The IMSAI uses a Versafloppy1 as opposed to the Versafloppy II in the SBC200. The IMSAI setup works fine.

    As a side note, the IMSAI can also boot the exact same Gotek disk Images as the SBC200. In fact I just maintain one library if disk images for both systems.

    Anyway, was wondering if anyone had any insights into my issue?
    retro computing at: dead

  2. #2
    Join Date
    Jan 2007
    Pacific Northwest, USA
    Blog Entries


    Does your floppy controller require a READY signal on pin 34? 235HF drives provide a "Disk changed" signal on that pin.

    So you insert a floppy, which causes DC to go active, but it looks like a READY signal to your FDC. Once the format is complete, the DC signal is reset and your drive suddenly looks not ready. If this is the case, it's easy enough fix--just ground pin 34 and the drive always looks ready.

  3. #3


    Hi Chuck..Thanks for the info. I'll look into that and let you know what I find.
    retro computing at: dead

  4. #4


    Well that was too easy.
    I grounded pin 34 and it worked first time.
    Much thanks!!!
    retro computing at: dead


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