Maybe the FDC is faulty. Try to disable (if you can) the onboard FDC and put an external I/O card.

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Zup wrote:

Maybe the FDC is faulty. Try to disable (if you can) the onboard FDC and put an external I/O card.

There is no onboard FDC, I'm using a FDC-III ISA controller already - and it does work with the 360k drive, but I suppose it could be having issues with the 3.5" for some reason. As far as I could tell from the datasheet it was supported, and since it's all in one chip I assumed since the one drive worked that nothing else was wrong with it. I'll get another FDC if I have to but was thinking it sounded more like a configuration problem somehow.

Predator99 wrote:

Did you try the same disk and drive combination that worked in the other machine?

Are you sure the disk you have tested is OK? Do you have tried to format it with 720K?

Disk was formatted and can read/write in the other machine - I then pulled that drive and cable out of that machine and tried it in the 286, same result - drive appears to engage but won't read anything.

I have not tried formatting with 720k yet though. I'll give that a shot.

Wait, the problem doesn't neccesarily mean the 286 board or the IDE/floppy card is faulty.
I have the exact same issue with one machine. With a pure floppy controller, the machine boots just fine.
Perhaps its BIOS is just somehow weirdly tied to WD1003 controllers or the IDE controller is causing trouble ?

Jo22 wrote:

Wait, the problem doesn't neccesarily mean the 286 board or the IDE/floppy card is faulty.
I have the exact same issue with one machine. With a pure floppy controller, the machine boots just fine.
Perhaps its BIOS is just somehow weirdly tied to WD1003 controllers or the IDE controller is causing trouble ?

I did wonder if the hard drive controller was conflicting somehow - I'll pull it out and see what happens.

The BIOS could still be giving me trouble - I'm not too familiar with this BIOS yet, and all I've managed to find is the standard setup so far, can't figure out how to set any advanced settings. I'm assuming there was a setup program but it doesn't seem to be on the drive.

Sorry, I'll admit, I haven't read all. If you are looking for one of the last (commonly available) 3.5" FDD's, look for an Alps model, they seemed to still manufactured around 2005-6. Additionally make sure that you have specified that you have a 1.44mb, 3.5" FDD in your computer BIOS. It's very possible that a drive is not set from that behaviour.

betamax80 wrote:

Sorry, I'll admit, I haven't read all. If you are looking for one of the last (commonly available) 3.5" FDD's, look for an Alps model, they seemed to still manufactured around 2005-6. Additionally make sure that you have specified that you have a 1.44mb, 3.5" FDD in your computer BIOS. It's very possible that a drive is not set from that behaviour.

Appreciate it, but I think I'm alright from both angles - I have three drives that work in other machines, and it's set to 1.44mb 3.5" in the BIOS.

Update: Yanked out the Seagate HDD controller, connected 3.5" at drive A on the cable and set the appropriate setting in the BIOS, still getting "disk not ready error" trying to boot. Drive spins, heads engage, and nothing. It's starting to look like a floppy controller to me, but then that doesn't explain how it worked with the 5.25" drive - can a controller just go bad for one type?

I'll try formatting one as 720k and see if the density makes a difference.

Well, so much for that. "not ready reading drive A"

If I try to format, it says "formatting 720k" and then "Not ready." and aborts.

I wish I had another controller to try. I might have to go buy one and give it a shot.

Well, finally found here: Re: My Future Super Turbo XT build someone that references the UM8397 being a low-density controller. I'd bet that's my problem. Time for a new floppy controller I guess 🙁

I remember when I had boxes of these things lying around, and gave them all to goodwill and places like that. Now they're all probably on eBay for $80 a piece. Oh well, guess that's how it goes.

sqeeek wrote on 2017-06-18, 06:27:

Hello! You guys have been a fantastic resource and I've just never got around to creating an account for some reason, but this o […]
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Hello! You guys have been a fantastic resource and I've just never got around to creating an account for some reason, but this one has me well and truly stumped. Most sincere apologies if this is already out there.

I have a 286 machine with AMI BIOS S286-6181-101590-K8. I'm booting into Dos 5.0 from an ST-277R on an ST11 card. The floppy controller is a UM8397 on a "FDC-III" 8-bit card.

I can't get it to read 3.5" disks to save my life. 5.25 works fine, even set to 720k in the BIOS on accident. I have two 3.5" drives that both work in a '98 Dell, one of which is dated 1991 and came out of a similar 286 machine. I've tried different cables, I've tried different disks - but nothing. Heads engage, drive makes noise, and A/R/F error trying to read or format the disk, even though the option for 1.44mb is in the BIOS and seems to be showing up correctly in DOS as well.

Do you wonderful people have any advice on where to look next?

Could you send me the content of this eprom? My motherboard came without and I can't find it anywhere. Would you have an eprom recorder to copy it?