Quirks like this could come from memory issues, have you tested the RAM?
It could also be a PCI busmastering issue.

I'll try just removing the RAM sticks I have and running off the 8GB on the CPU board (gonna be a bigger repair if it's bad). I did notice that Windows 95 only intermittently recognizes my 24MB; usually it reports 22MB. I've always wondered about that.

How would I check for a bus mastering issue? The controller reports it being on, but there are no settings for it in the motherboard BIOS that I can see.

Most likely an eide/cf incompatibility. It is common.
Look here and here.
Promise vlb controllers are ok speed-wise, but quite reliable with cf cards.
Still, nobody is insured against mixing tech with such a large generation gap.

mcyt wrote on 2021-03-24, 01:41:

I'll try just removing the RAM sticks I have and running off the 8GB on the CPU board (gonna be a bigger repair if it's bad). I did notice that Windows 95 only intermittently recognizes my 24MB; usually it reports 22MB. I've always wondered about that.

How would I check for a bus mastering issue? The controller reports it being on, but there are no settings for it in the motherboard BIOS that I can see.

Wouldn't hurt to do a run with memtest86 just to rule it out.

To see if it had any effect you'd have to turn it off in the BIOS settings, but since it's a Compaq I'm really unsure if that is possible. Older PCI implementations did use slave PCI slots which were not too happy with busmastering devices. If your system has one of those, maybe try another PCI slot. The busmastering would only affect the Promise controller, not the internal IDE.

Also is the firmware on the CF card(s) set to fixed disk, or removable storage? If it's not set to fixed disk then that is most likely your answer since error 1740 is "Fixed Disk 0 failed Set Block Mode command" on Compaq.

Other threads to check regards to this:
- Can't Boot from Compact Flash
- Deskpro XL 590 restoration - questions
- Compaq CF video (includes 1740 error): https://www.youtube.com/watch?v=BFE7D8wk9AM

I am aware of that video, as it's mine 😀

I've seen those other threads as well, but I didn't know until today that there's a way to set fixed disk mode if it's not already set. Transcend says that their industrial cards are already set to fixed disk mode, so mine probably is, but I'll double check that.

I ended up trying a whole other processor board with different memory, and oddly Windows still didn't recognize all of it. The BIOS does.

I did read several other threads from people who have this controller who seemed to have the same problem with real hard drives, so I have a feeling it's just some controller incompatibility at this point. (One guy with Western Digital drives was even told by Promise that outright.) In another thread, someone had this issue with CF cards and the people trying to help him suggested that the reset signal somehow was not reaching the card, but there was no resolution to that that I saw.

Well, I'll check the fixed disk thing later. I've also just ordered a real SSD at this point, which also may or may not work, but even if it does I still want to try getting the CF card fully working since it's still a good way to transfer files between PC's.

I was not aware of that! I have watched many of your videos, great content!

It's easier to get a CF card working as a removeable disk as D: or similar if you got another fixed disk setup. I personally have not encountered any issues installing a CF card in my Compaq Presario 4766, but that is a much newer system (Intel 430VX chipset, Socket 7) than your 486. I did have issues with a Promise S-ATA controller (to install an SSD drive) which would not support boot from BIOS, so I used my CF card as boot drive just to get Windows loaded from the SSD.

vetz wrote on 2021-03-27, 12:21:

I was not aware of that! I have watched many of your videos, great content!

Thanks, and no worries, I'm not trying to promote myself or anything so didn't really expect anyone to make the connection. But it's just funny to get my own video recommended to me for reference 😀 And you guys are getting a follow-up to that video right now...

I'm now back to thinking it's something about my CF cards, and I've ordered another industrial card (this'll be my fourth card, though only the second industrial). I re-read that Deskpro XL 590 restoration thread and the OP there fixed his 1740 error just with a new card. He also said he fixed his problems soft-booting on his Promise controller that way. It's been a while now but I believe that's probably why I bought a Transcend industrial card in the first place (that's what he bought), though mine might be a different series. Mine is a CF300 series.

I did try both methods I found to try to set fixed disk mode on all my cards (ATCFWCHG.COM and BootIt) and the former failed outright on all of them while the latter said it worked but I still got the 1740 Set Block Mode Command Failed error. When looking up the specs of the card I ordered today, I noticed it listed "multi-sector writes" as a feature, which is what block mode does, and that implies to me that not all CF cards have that if they felt it was a selling point to list it. So as always I'm hopeful, but literally nothing I've tried so far has worked to fix this, so I'm still also doubtful.

At this point I just want to get it working on either controller; I'm sort of mixing up talking about both controllers in this thread, on-board and the Promise controller. Ideally I can find a solution that works on both, which will give me flexibility.

btw my SSD card and adapters for it arrived and that didn't work either. I knew it only had a chance on the Promise controller but since it's an ATA100 controller with a BIOS that recognizes drives up to 137GB, I thought it had a good shot. DOS installed to it but then it hung on boot every time. The Compaq configuration utility also wouldn't install to it or create a system partition on it. (Though that may be the case for any drive on a separate controller.) Even before that, there were weird issues like the drive just suddenly dropping out as if it had been unplugged, or the computer taking forever to recognize it when doing fdisk or whatever. So I'll just use it in another, slightly more modern computer.

The Deskpro is probably going to have to figure out how to work with CF. Hopefully it's still just a problem with my specific cards.

mcyt wrote on 2021-03-28, 06:39:

The Deskpro is probably going to have to figure out how to work with CF. Hopefully it's still just a problem with my specific cards.

Lets cross our fingers for that. If not, it's going to be hard to come to the bottom of this unless you'd want to spend alot of time with trial and error (it looks like you've spent too much already 😜)