CF cards for the generic xt at compatible adapters is 2gb max cannot access in UDMA 7 mode there are pin instructions on the web to cure that but theres no cf adapters i have found for udma 7 or i'd use it on my ATA66 machine which did same thing and i cant be stuffed modding the layout maybe you can.
You will find full capacity booting from floppy or other device that is compliant until you get a UDMA7 compatible adapter (or mod).

Sphere478 wrote on 2022-06-05, 04:18:

Hmmm, yeah that’s kinda limiting.

I have an idea,

What about a soundblaster, plug the compact flash into the soundblaster ide, and try using plop to boot to it from another device like gotek, flopy, cd or a second cf on primary ide

That's really interesting, I didn't know about plop and never though to try and connect it to my Vibra16 interface. I do have a Gotek (with FF) installed on this machine... but I think this would be a last resort especially since booting would be painfully slow on an otherwise beast of a 486 system. I still think XTIDE is the best alternative to using the onboard controller... I read up on my particular XTIDE board and it has a high performance mode, but it requires the rom to be flashed to enable that and I'm skeptical how fast an 8bit card can be... my guess is it's less compatible and marginally faster, but I need to try it out to see. I really want to get a rom flasher before I start messing stuff up with my working XTIDE, so I'm waiting for one to arrive from ali express. I also prefer to flash a rom on a NIC card approach for this particular machine and see how that goes (way cheaper than buying an XTIDE card). I've pretty much given up on the existing bios as I've literally toggled every relevant setting in the bios.

Anyway, thanks for even more info to consider, I learned a ton in this thread.

zapbuzz wrote on 2022-06-05, 05:21:

CF cards for the generic xt at compatible adapters is 2gb max cannot access in UDMA 7 mode there are pin instructions on the web to cure that but theres no cf adapters i have found for udma 7 or i'd use it on my ATA66 machine which did same thing and i cant be stuffed modding the layout maybe you can.
You will find full capacity booting from floppy or other device that is compliant until you get a UDMA7 compatible adapter (or mod).

I'm not all that interested in getting full capacity out of my 32gb card, the DOS limit of around 8gb is fine. It's just the reliability of the file transfers that's the issue. I did some searching and noticed that this CF IDE supports (multi-word/ultra) DMA and PIO...
https://www.amazon.com/Syba-SD-CF-IDE-Connect … B000TMDE6G?th=1

Now I'm wondering if my Startech CF IDE doesn't. I can't find any info on what modes are supported.

bstar wrote on 2022-06-05, 12:35:

Sphere478 wrote on 2022-06-05, 04:18:

Hmmm, yeah that’s kinda limiting.

I have an idea,

What about a soundblaster, plug the compact flash into the soundblaster ide, and try using plop to boot to it from another device like gotek, flopy, cd or a second cf on primary ide

That's really interesting, I didn't know about plop and never though to try and connect it to my Vibra16 interface. I do have a Gotek (with FF) installed on this machine... but I think this would be a last resort especially since booting would be painfully slow on an otherwise beast of a 486 system. I still think XTIDE is the best alternative to using the onboard controller... I read up on my particular XTIDE board and it has a high performance mode, but it requires the rom to be flashed to enable that and I'm skeptical how fast an 8bit card can be... my guess is it's less compatible and marginally faster, but I need to try it out to see. I really want to get a rom flasher before I start messing stuff up with my working XTIDE, so I'm waiting for one to arrive from ali express. I also prefer to flash a rom on a NIC card approach for this particular machine and see how that goes (way cheaper than buying an XTIDE card). I've pretty much given up on the existing bios as I've literally toggled every relevant setting in the bios.

Anyway, thanks for even more info to consider, I learned a ton in this thread.

No prob 😀

Interested to hear what you come up with.

I’m curious if plop will see it on the card. I give it a 50/50

Have you tried with an old CF card of low capacity? Say 256 or 512MB? These usually only support PIO for transfers and is a good way to rule out DMA as the cause of issues, as even if there's no way to enable it on the BIOS, the adapter could take issue with it.

bstar , any chance of getting a photo of the mainboard & ide controller ?
preferably with the text on the ics readable.

devius wrote on 2022-06-05, 16:44:

Have you tried with an old CF card of low capacity? Say 256 or 512MB? These usually only support PIO for transfers and is a good way to rule out DMA as the cause of issues, as even if there's no way to enable it on the BIOS, the adapter could take issue with it.

I can try to rule it out... do you think a 1gb Sandisk Ultra II card would suffice?

weedeewee wrote on 2022-06-05, 17:17:

bstar , any chance of getting a photo of the mainboard & ide controller ?
preferably with the text on the ics readable.

Sure. I need to disassemble the machine, but I can get a pic. I did some damage on the backside trying to get the RTC out several years ago, so there's a fixed broken trace on the backside.

bstar wrote on 2022-06-05, 18:59:

I can try to rule it out... do you think a 1gb Sandisk Ultra II card would suffice?

Maybe. From what I could find the Ultra II is more or less from the time when Sandisk started making cards with Ultra DMA capabilities, but it's not clear if this line already has that feature or not.

devius wrote on 2022-06-05, 20:57:

bstar wrote on 2022-06-05, 18:59:

I can try to rule it out... do you think a 1gb Sandisk Ultra II card would suffice?

Maybe. From what I could find the Ultra II is more or less from the time when Sandisk started making cards with Ultra DMA capabilities, but it's not clear if this line already has that feature or not.

I found an ancient 128mb card and setup my diagnostics on it. This card is not experiencing any issues, so it might indeed have something to do with ultra dma.

That would be a easy one to solve if it’s just the card! :p

Sphere478 wrote on 2022-06-06, 04:03:

That would be a easy one to solve if it’s just the card! :p

It gets me a bit closer to a solution, but using a 128mb card isn't exactly ideal. I know I've had similar issues with my 2gb Verbatim card, so it probably is related to DMA support. I think the only fail proof option is to admit defeat and bypass the bios' ide controller in favor of an XTIDE solution. I'll know in a couple weeks how that works out when the stuff I ordered arrives.

I really appreciate every one's help and suggestions.

Could also be a problem with the adapter itself. If you can find one that uses a completely different IC you may have some luck.

devius wrote on 2022-06-06, 21:06:

Could also be a problem with the adapter itself. If you can find one that uses a completely different IC you may have some luck.

I think many of the ide to cf adapters are basically passive devices aside from some power circuitry

devius wrote on 2022-06-06, 21:06:

Could also be a problem with the adapter itself. If you can find one that uses a completely different IC you may have some luck.

This adapter works perfectly in a DX4 100 machine I have with the same card (It's a Biostar socket 3 PCI board). I have another cf/ide adapter (different brand) and it's even more unstable in the problem machine... sometimes that one won't even boot.

Sphere478 wrote on 2022-06-06, 21:36:

I think many of the ide to cf adapters are basically passive devices aside from some power circuitry

Good point! And yet, somehow they don't all behave the same.

devius wrote on 2022-06-07, 17:53:

Sphere478 wrote on 2022-06-06, 21:36:

I think many of the ide to cf adapters are basically passive devices aside from some power circuitry

Good point! And yet, somehow they don't all behave the same.

do you imply different adapters behave differently in the same machine

that's totally possible

I know there is a mod for 80 pin detection. Think this may be at play here?

There may be other differences. it would be nice to learn of them. To more fully understand what's happening here.

I also have no idea 😆 Whenever I have compatibility issues I just try a bunch of combinations of adapters and cards until it works.

devius wrote on 2022-06-07, 20:22:

I also have no idea 😆 Whenever I have compatibility issues I just try a bunch of combinations of adapters and cards until it works.

A time honored approach we are all guilty of. 😂

i found this to read it was very informative and has links to pinouts http://support.fccps.cz/download/adv/frr/cf.html