Hi, I'm a former SLT 286 owner. I don't if I can help, however.

My SLTs had HD floppy drives, but maybe yours is a DD one?
It's just a wild guess. The SLT 286 is very old. It's unlikely, but possible that your model had an DD drive.

Jo22 wrote on 2022-12-14, 09:03:

My SLTs had HD floppy drives, but maybe yours is a DD one?
It's just a wild guess. The SLT 286 is very old. It's unlikely, but possible that your model had an DD drive.

Thanks for your reply. I assume that "DD" is Double Density?

The Floppy model in it is a Citizen 0SDA-53B, from what I understand can do 1.44MB. But for reasons I forget right now, the setup floppy must be a 720KB (which it is)

Catbones wrote on 2022-12-14, 10:28:

Thanks for your reply. I assume that "DD" is Double Density?

You're welcome. I just wished I could offer better help.

Yes, right. ^^

Catbones wrote on 2022-12-14, 10:28:

The Floppy model in it is a Citizen 0SDA-53B, from what I understand can do 1.44MB. But for reasons I forget right now, the setup floppy must be a 720KB (which it is)

Ah, ok. It was just an idea. You can try using an 1,44MB HD floppy in 720 KB floppy "mode" with a bit of tape.

But firstly, you must format/overwritte the whole HD floppy in your 1,44MB drive.
Then, you can mask the hole on the other side of the write-protection tab.

Then, the floppy drive thinks the floppy is a 720KB DD floppy.
The PC will complaing about the disk not being formatted, maybe a "sector 0" error will appear.
- Ignore that. Use WinImage and write a 720 KB image to the drive (ideally, the one with the Compaq software)). Use formatting option only if needed.

Anyway, these are just ideas. If you have a spare blank floppy for experiments at hand.
But they worked for me in the past. For other vintage PCs, not the SLT 286 in paricular.

Edit: These are just ideas, as I said. Don't worry if it doesn't work.
Also, I'm not the only SLT 286 owner here. There are at least two more, afaik.
Maybe they have a clue how to help.

Because, I was tinkering with my SLTs about twenty years ago, afaik.
So I did forget certain things. Anyway, I was brave and fixed one SLT 286 in the past. 😁
Back then, I remember, I disassembled one unit and changed the CMOS battery and upgraded the proprietary RAM to 4MB.
It was a wonderful Windows 3.1 computer, back then. When on the go or in living room, I did all my Visual Basic programming on it.

Jo22 wrote on 2022-12-14, 13:27:

Ah, ok. It was just an idea. You can try using an 1,44MB HD floppy in 720 KB floppy "mode" with a bit of tape. […]
Show full quote

Ah, ok. It was just an idea. You can try using an 1,44MB HD floppy in 720 KB floppy "mode" with a bit of tape.

But firstly, you must format/overwritte the whole HD floppy in your 1,44MB drive.
Then, you can mask the hole on the other side of the write-protection tab.

Then, the floppy drive thinks the floppy is a 720KB DD floppy.
The PC will complaing about the disk not being formatted, maybe a "sector 0" error will appear.
- Ignore that. Use WinImage and write a 720 KB image to the drive (ideally, the one with the Compaq software)). Use formatting option only if needed.

I have got proper 720KB floppies and have used Compaq's software to make the diagnostic disks myself multiple times seemingly without error. But either using those or trying 1.44's with the tape method I'm still greeted with the "Load Failure" message.

I'm wondering if there's something else I can do to verify that the drive is able to read anything at all. Transplanting it in to another system seems my best bet, but the right adaptor for that is proving elusive. So far I haven't seen anyone use a floppy drive emulator in one of these machines.

I have one too. It did have the same issue: it would not read a verified healthy DD disk (real dd, not modded hd).
I ended up taking the drive apart and clean the heads with isopropyl and a thin cloth. That helped and now it reads the disks fine 😀
(It had the Dallas mod as well)

waterbeesje wrote on 2022-12-14, 18:01:

I have one too. It did have the same issue: it would not read a verified healthy DD disk (real dd, not modded hd).
I ended up taking the drive apart and clean the heads with isopropyl and a thin cloth. That helped and now it reads the disks fine 😀
(It had the Dallas mod as well)

Thanks for the info, that sounds promising!

I had avoided taking things apart as much as possible up to this point in case I ended up creating a new problem. Now I know that a simple clean has fixed a similar issue I will give it a go.

waterbeesje wrote on 2022-12-14, 18:01:

I have one too. It did have the same issue: it would not read a verified healthy DD disk (real dd, not modded hd).
I ended up taking the drive apart and clean the heads with isopropyl and a thin cloth. That helped and now it reads the disks fine 😀
(It had the Dallas mod as well)

No luck unfortunately. I gave the heads a wipe with IPA, but they were already clean as a whistle. Still getting the same error.

I tried creating new disk from the SP0308.exe, as well as formatting a 720KB DD floppy with WinImage as suggested above and using the .img of the setup disk from here Help getting Compaq Diagnostics/Setup floppy image on real floppy? but same problem as before.

I can get a "Non system disk" error if I put a blank floppy in the drive, so it must be able to read something. Any attempt at using an HD floppy wil make the machine lock up.

Any floppies that failed to format got binned. So I know I only have good ones left.

Catbones wrote on 2022-12-14, 17:47:

I have got proper 720KB floppies and have used Compaq's software to make the diagnostic disks myself multiple times seemingly wi […]
Show full quote

I have got proper 720KB floppies and have used Compaq's software to make the diagnostic disks myself multiple times seemingly without error.
But either using those or trying 1.44's with the tape method I'm still greeted with the "Load Failure" message.

I'm wondering if there's something else I can do to verify that the drive is able to read anything at all.
Transplanting it in to another system seems my best bet, but the right adaptor for that is proving elusive.
So far I haven't seen anyone use a floppy drive emulator in one of these machines.

Oh, sad to hear. 🙁

Hm. In theory, XTIDE Universal BIOS perhaps could help with its boot over serial feature (there's a PC program that simulates a HDD)..
But that means you had to combine it with the BIOS somehow and write it into a new EPROM chip.

Some other users did that with a Toshiba laptop, it was a T3200 or something..

The good thing about XTIDE BIOS is, that it can co-exist with the BIOS' own HDD code.
So maybe you could use that to have two HDDs in the system - the internal one and the simulated one (via V.24 port).

Anyway, this is just another idea.

Could there be some bad caps? These may also make the drive act like this.
I've seen it with my IBM model 30s

Jo22 wrote on 2022-12-15, 08:08:

Hm. In theory, XTIDE Universal BIOS perhaps could help with its boot over serial feature (there's a PC program that simulates a […]
Show full quote

Hm. In theory, XTIDE Universal BIOS perhaps could help with its boot over serial feature (there's a PC program that simulates a HDD)..
But that means you had to combine it with the BIOS somehow and write it into a new EPROM chip.

Some other users did that with a Toshiba laptop, it was a T3200 or something..

The good thing about XTIDE BIOS is, that it can co-exist with the BIOS' own HDD code.
So maybe you could use that to have two HDDs in the system - the internal one and the simulated one (via V.24 port).

Anyway, this is just another idea.

XTIDE looks like quite a complex solution. I'll keep it in mind, but as an "if all else fails" option.

waterbeesje wrote on 2022-12-15, 08:34:

Could there be some bad caps? These may also make the drive act like this.
I've seen it with my IBM model 30s

It's certainly possible! Testing all the tiny SMC's on the boards of the drive would keep me occupied for a while.

In the mean time I have found and ordered an adaptor that should let me either hook up a 34 pin floppy to the SLT, or the dubious 26 pin drive to a desktop PC for testing.