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Thread: Tandy 2000 and 3.5" floppy conversion

  1. #1

    Default Tandy 2000 and 3.5" floppy conversion

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    I'm pulling this topic into a separate thread to make it easier to find. I want to add a 720K 3.5" floppy to my Tandy 2000. So, I've done a bit of searching and bought a couple of different floppy drives. The most promising, based on recommendations, is the Samsung SFD-321B. The model I have specifically is for IBM (SFD-321B/MBM2). It seems to have the same controller board as this one: http://jope.fi/drives/sfd321b-lcp3/ although the drive I have didn't have the NHDD pad soldered as in Step 2 in the picture. I also made the pin 2 connection which theoretically isn't needed because pin 2 isn't used on the Tandy 2000, but I connected it anyway.

    Making the mods was very easy, but definitely use a magnifier because the pads are small. Unfortunately, it doesn't work.

    Has anyone gotten this working and if so, what drives have people used?

    Thanks!

  2. #2
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    Does the drive spin up? Have you tried installing it as a: and b: ?

  3. #3

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    Quote Originally Posted by 2icebitn View Post
    Does the drive spin up? Have you tried installing it as a: and b: ?
    No, and just A. I’m thinking there’s a jumper I need but the manual I have doesn’t have any jumper definitions in it. I have to test it on a PC to confirm it works there. I also found a 720k drive from a 1000EX that I want to try, a Teac FD-35.
    Last edited by RichCini; January 5th, 2019 at 10:24 AM.

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    Woah--that's way more than you need to do on the Samsung drive. The Amiga mods have less to do with simple signals.

    See the OEM manual here.

    The most you'd have to do is to set it up for pin 34 = READY and maybe DS0.

  5. #5

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    Thanks, I've referred to that manual before. It's a little light on information on the less-important jumpers. The Amiga conversion boils down to 4 things, two of which are the same as yours. The 3rd relocates the disk_change to pin 2 (likely not needed; pin 2 is unused on the T2K) and removing the NHDD jumper (which was open on my drive already; no idea what it does).

    Will noodle around with this later today.

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    If you get lost, I'll pull one of my drives out and tell you what I'd change.

    Does the T2000 use DS0 for the first drive select or is it the PC scheme (every drive is DS1; there's a twist in the cable)?

  7. #7

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    Ok, some additional info. The INUSE/NHDD jumper connects to pin 2. I un-did the pin 2 mod and added the INUSE jumper since the T2K has this signal. Now, the activity light goes on at the right time but the motor doesn't spin when the drive is accessed, so it has to be something with the motor signal. Same thing on the FD-35 drive from the 1000EX.

    It's straight cabling and by default, the cable is a single-drive cable. If I can get this working, I'll make a two-drive cable.
    Last edited by RichCini; January 5th, 2019 at 11:42 AM.

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    Did you change the "drive select"? On my drives, it's a solder bridge near the lower right part of the PCB near the connector. The bridge uses the second drive select and I think you want the first one. Motor on/ should be the same on all drives (pin 16)--that one hasn't changed. You can test it by grounding that pin--it operates independently of select.

  9. #9

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    I just found this:

    https://electrickery.hosting.philpem...c/notejump.pdf

    Definitely going to save this. 670 pages of information on jumpers and configurations of all Tandy computers.

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    Note that the 'In use" LED coming on isn't necessarily indicating a valid "Drive Select". Do check your drive select.

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