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Thread: Original Tandy 1000 no boot

  1. #51
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    Yeah, I don't think the cable it came with is original:

    https://drive.google.com/file/d/1kPc...ew?usp=sharing

    If you look really closely you can see the connectors' pin 1 is on the same side as the striped wire. The machine came with that cable and two Toshiba FDD5401 floppy drives. I don't know how it could have worked.. the way it appeared to be set up, pin 1 of the header connector was plugged into pin 34, and then pin 1 of each drive connector was into pin 1 of each Toshiba drive. I don't see any evidence the cable was folded or anything to allow aligning the header to pin 1 properly.

  2. #52
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    Come to think of it, maybe this cable is correct. The TEAC drives have their PIN 1 on the opposite side that the Toshibas and most other drives do.. so even if you plugged this cable in 'wrong' with the striped wire connecting to PIN 34, it would still be correct as 'pin 34' on this cable would now actually be pin 1.. weird way to do it though.

  3. #53
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    Not sure why the cable didn't come with a key so that you don't plug it in backwards (though you could still connect it backwards at the motherboard header), but whatever.
    Does the drive just stay spinning all the time, or only when you try to access it?
    Could you give us the model number of the drives, as well as list what the jumpers on both are set as? I'm wondering if maybe somebody didn't knock a jumper loose by accident. The drives should be jumpered as DS0 and DS1 (for A: and B: respectively), and the motor control jumper should be set to MS instead of MM (to use the Drive Select signal), since Shugart controllers only use one motor control line (pin 16)
    My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

    Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

  4. #54
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    Many thanks.. I will dig out this info tomorrow.

    Basically what happens is you power on, and drive A immediately lights up and the motor spins. It does not react or change in any way as the machine goes through its post cycle.

    Thinking about it now I'm not sure how this set up could ha e worked. As I recall the cable was lined up straight, so pin 1s and 34 would have gotten reversed by the time they got to the drives. But it does look like they were installed for some time.

    I am looking around for a TEAC replacement.. prefer those with Tandy. Just trying to figure out which model they used.. think it was FD-55B or B-U?

  5. #55
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    If the light comes on and the motor spins endlessly as soon as itís powered on thatís the classic sign of the floppy connector being plugged in backwards. Iím a veteran of having done that more than once on my TRS-80s and the Tandy 1000 uses the same Shugart wiring scheme.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  6. #56
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    Quote Originally Posted by Eudimorphodon View Post
    If the light comes on and the motor spins endlessly as soon as it’s powered on that’s the classic sign of the floppy connector being plugged in backwards.
    Done that myself more than a few times. Especially confusing on Tandy's 3.5" drives, because the key notch is on the opposite side of the connector.

    If both drives are spinning right on startup, then reversing the connector on the motherboard so that pin 1 on the header lines up with pin 1 on both slot edges ought to fix that problem. If this is happening only on one drive, then it's probably a jumper issue. Might be a good idea to snap photos of the jumpers on both drives and give each a temporary label before we go messing with them.

    Quote Originally Posted by Eudimorphodon View Post
    the Tandy 1000 uses the same Shugart wiring scheme.
    I wonder why Tandy decided to keep up with the Shugart scheme long after they abandoned the external floppy port. Probably made comparability easier within their own product lines, but it makes things a pain if you're trying to use third party 3.5" drives. It's not just the original 1000, but as far as I can tell, they used it right to the end of the line with the RSX, as I stumbled upon when I had to replace my RSX's floppy. Not sure about the other Tandy lines, but I know the 2500RSX is basically the same motherboard as the 1000RSX, so they might have even done this for all of their systems.
    My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

    Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

  7. #57
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    I have tried orienting the cable both ways.. being careful to make sure pin 1 on the header connects to pin 1 on the drive results in what I described: drive A spinning endlessly. If the cable.is reversed, both drives light but don't spin.

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  9. #59
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    Right away I notice that the drive set as DS2 (seems they start at 1 instead of 0) is missing a bunch of jumpers from PJ5. That's probably for the terminator resistor pack (the white chip between the jumper blocks). Like SCSI, the terminator would be enabled on the last drive on the cable. If drive 1 was at the end of the cable, that should be fine, though it probably ought to have another jumper across position 1 too, if that's what it is.

    I can't find an exact match for FD5003, but I found a PDF that appears to have similar jumper configuration on page 2: http://blog.3b2.sk/igi/file.axd?file...25-jumpers.pdf
    Based on that, both drives are set to have the LED come on when the drive is selected, rather than by the "in use" signal, and the heads are loaded by the "motor on" signal rather than "drive select."
    The jumper for RM/DM doesn't appear to be populated on either, so I don't think that's the cause.

    I see test points sticking up from the board. Maybe check between the "RY" test point (between C10 and C11) and ground with a multimeter, and see if the state changes when you try to access the drive.

    Before going further, I'd stick a label on both drives so you can tell them apart. I'm thinking that if populating the T1 position of JP5 doesn't solve the problem on the A: drive, then try populating the JP5 block on the B: drive and setting it to DS1, then try to boot from that with only the one drive. If you can boot that way, and the drive behaves normally, then we'll know it's something with the drive and not the controller.
    My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

    Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

  10. #60
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    Ok many thanks.

    Just FYI - I've also tried this with a 360K panasonic drive from a Commodore PC10 that does exactly the same thing. I'll have to get a pic of the jumpers but it worked fine as an A drive in other machines, and the Toshiba configured as A has worked in other machines also.

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