floppy drive confusion \ VOGONS

floppy drive confusion

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First post, by ratfink

Posted on 2014-02-27, 18:16

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I have a winbond ISA card that includes a floppy controller, it's a AB-757 GV2, I cannot find the jumper settimgs on the web.

I have it connected to a 5.25" and a 3.5" drive.

Starting from the controller card end, the cable has (1) a 3.5" drive connector , (2) a 5.25" connector, then after a twist, it ends with (3) another 3.5" connector. I attach the 3.5" to the final one (3).

Booted like this, the 3.5" drive works as A: and I have been able to install DOS to the hard disk.

When I add a 5.25" drive, both drives grunt and groan and flash their LEDs during boot [3.5" then the 5.25"], but although the bios shows both, when I go into DOS not only is the 3.5" named A: [which is what I want] but trying to access B: it asks me to swap the floppy in A:. It's as though it cannot detect the 5.25 drive even though the drive made the right noises during boot [which I thought meant the bios was checking it was operational].

When I remove the 3.5" drive from the cable, the 5.25" drive can be accessed as B:.

I have used this controller before with two drives, and the jumpers have not been changed since.

Any ideas?

Edit: Another issue with this 5.25" drive. It will only format floppies to 160k. Though it will format to either 160 or 320 [using format /f:160 etc], in each case the disk only ends up being 160k. Is that normal?! 🤣 Any other format size-related parameters [other that /8 which is the same as 160 or 320] are refused.

Reply 1 of 7, by Jorpho

Posted on 2014-02-27, 19:06

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I thought 3.5" floppy drives and 5.25" floppy drives used the same connector, but then I haven't seen a 5.25" drive in a long time.

What two drives were you using this controller with before? If it wasn't the same setup you have now, it sounds like you need new jumper settings.

Reply 2 of 7, by ratfink

Posted on 2014-02-27, 19:13

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3.5" has pins like a small ide connector

5.25" normally has an edge connector sticking out the back

I may have used a different 5.25 drive before.

I seem to recall issues with trying to make the 5.25 the B: drive so maybe I need a different cable [or jumpers, as you say].

Reply 3 of 7, by bristlehog

Posted on 2014-02-27, 20:28

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Usually a floppy cable would have a 3.5 connector for controller, then 3.5, 5.25, then twist, then 3.5 and 5.25 again.

Your connection seems right, but you may try another cable.

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Reply 4 of 7, by pyrogx

Posted on 2014-02-27, 22:06

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The DS (Drive Select) jumpers on each floppy drive need to be set correctly. There should be four jumpers named DS1-4 or DS0-3 near the connector on the rear side of the floppy drive. Drive A needs to have DS1 set and drive B DS2.

Reply 5 of 7, by ratfink

Posted on 2014-02-27, 22:56

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thanks. my cable lacks the final 5.25 connector, but the way I have it the 5.25 is at the B connector and the 3.5 is at the A side of the twist.

just pulled the drives out - the 3.5 is pretty much fully encased, no jumpers visible. the 5.25 has 4 jumpers on the pcb underneath. it's set at the second jumper from the far end.

moving that jumper to the third position and rebooting - both floppy drives seem to think they are A:.

ijust tried with another 3.5 inch floppy drive [different make but also no jumpers visible]. exactly the same.

Reply 6 of 7, by Jepael

Posted on 2014-02-27, 23:05

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So both drives work alone but not when both are simultaneously connected?

It could be that both drives have terminated the signals, and back in the day 5.25" drives had stronger termination resistors and also back in the day floppy interfaces could drive heavier loads. Maybe putting both drives there is too much load for the floppy interface to drive.

Reply 7 of 7, by ratfink

Posted on 2014-02-28, 09:19

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OK problem solved after a fashion. Dug out a full length floppy cable with all the connectors as per picture above. Now got both drives working together but only with the 5.25 as A: and the 3.5 as B:.

Thanks for the input, much appreciated.

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