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Problems with CF cards and SATA-IDE on 486

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First post, by Bobbi

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Hi folks,

Long time lurker, first time poster. I recently found a 486 in the garbage, and it sparked some enthusiasm to bring it back to life. The original mainboard had been damaged beyond my abilities to repair, so I procured a replacement motherboard on eBay, which seems to work fine. The board is an MV035 "Green Function VL-Bus System Board" with 486DX-33, 8MB (in two 72 pin SIMMs) and 128K of L2 cache. Chipset is Opti. The video card is a VLbus Cirrus Logic and there is an ISA multi-io card with a Goldstar chipset (IDE, FDC, 2S, P, game). System works fine and I can boot Slackware 3.3 from 3.5" floppy. Yay!

I don't have a PATA HDD, so I though to use a CF card. As it happened, I already had one of the popular/cheap two slot CF card adaptors "CF-IDE40 V.E0 (Double/DMA/3LED) and a few CF cards (adaptor and cards borrowed from my Apple II which has an IDE controller card ...) I had no luck whatsoever with this adaptor in the PC. I am plugging it directly into the IDE connector on the multi-io board. If the adaptor is populated with a 512MB CF card (smallest one I have) then the machine doesn't POST - video doesn't even initialize. If I remove the CF card and have just the empty adaptor connected to the IDE then I get an HDD Controller Failure and FDD Controller Failure from the BIOS.

I decided to try a different tack and bought a Startech IDE-SATA converter, which some folks seem to have had success with here. Hooking up a SATA drive (I tried a few, all pretty large by 486-era standards) I am able to 'Auto Identify' the drive in the BIOS, although it gets nonsense values. However on attempting a boot, I get FDC Controller Failure again, which seems odd. Why should hooking up an HDD cause the floppy drive controller to crap out? I have not confirmed 100% whether it is talking to the drive - I guess I may try and put a LILO boot block on it or something and see if it can at least load the MBR block. If I disconnect the SATA HDD and leave the converter connected to the IDE, the machine works again and I can boot from floppy.

Does anyone have any insight into why neither the CF or the SATA converter seem to work on this particular multi-io / 486? I find it very mysterious that we get the FDC failure with both the CF and the SATA connected.

At this point I just want to get a working mass storage device of some description. Any suggestions what I should buy, other than an ancient IDE drive? I don't want to keep buying devices if they're not going to work. Maybe I should find a different multi-io controller?

Reply 1 of 5, by rasz_pl

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1 IDE cable plugged wrong way into CF converter
this results in black screen, can happen with empty converter if it connects some pins to ground

2 CF cards and SATA/PATA converters might drive ALE according to newer ATA standards, older computers wire ALE straight to CPU bus and bad things happen
pin 28 Re: "Fixed" 386sx motherboard works but not with 16-bit VGA card

3 486 wont be able to detect large drives

4 "None of the SATA adapters control the -IOCS16 line, so they’re really designed for DMA transfer only where the line is ignored. PIO is expecting -IOCS16 to be pulled low if 16bit data is presented on the bus" Re: SATA HARD Disk in 286/386 Mobo: Is it possible?
TLDR: PATA-SATA converter might not work without some hacking (adding 2 ICs to generate missing signal)

5 even if you make PATA-SATA converter work it wont support PIO block mode = transfers one sector at time = slower than expected from SSD. CF seems optimal.

Last edited by rasz_pl on 2024-10-30, 17:11. Edited 2 times in total.

https://github.com/raszpl/FIC-486-GAC-2-Cache-Module for AT&T Globalyst
https://github.com/raszpl/386RC-16 memory board
https://github.com/raszpl/440BX Reference Design adapted to Kicad
https://github.com/raszpl/Zenith_ZBIOS MFM-300 Monitor

Reply 2 of 5, by vstrakh

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Bobbi wrote on 2024-10-30, 15:56:

Does anyone have any insight into why neither the CF or the SATA converter seem to work

With CF it's quite common that the adapter itself has the pin 28 grounded directly on the IDE connector. It's acceptable if such adapter is used with onboard IDE interfaces supporting "cable select" feature, in which case the pin 28 is grounded on the motherboard side, and then the cable would have a cut in that line between two last connectors. That how's hdd would know where it sits on the cable - before or after the cut. Grounding pin 28 on the adapter side is a mistake, but it's not essential in case of "cable select" enabled controllers.

Now with ISA multi-i/o cards the picture is totally different. The pin 28 carries the ALE signal from the ISA bus, often unbuffered. Just plugging such CF adapter into multi-i/o board grounds the signal that is critical for the system. Sometimes it works, the cards would see the edges in ALE signal (it takes some nanoseconds for ALE to propagate over long-ish ide cable and reflect back). Sometimes it's not.

Considering you have a 486-based system with ISA multi-i/o card - it's definitely not the "cable-select" enabled IDE controller. Inspect your CF adapter, see if the pin 28 on the IDE connector is grounded (joined with neighbors in large blob trace). You should disconnect that pin, either by cutting the trace around it to isolate from the ground, or by cutting out the pin itself.

Reply 3 of 5, by Bobbi

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Hmmm, thank you! I think you are onto something with this pin 28 ALE signal. I will see if I can find a way to disconnect that pin cleanly, and then see if it makes any difference!

Reply 4 of 5, by Bobbi

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It's not that easy to mod the CF adaptor since it is a female connector, but I did bend pin 28 of the IDE-SATA converter to one side so it doesn't connect. And ... I still get a FDC Controller error with the drive connected. So I don't think it is pin 28 (or not only pin 28.)

Reply 5 of 5, by Bobbi

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Well in the end I found an old 6GB EIDE laptop HDD from a Compaq Armada 7400 and it works perfectly with a 40 pin -> 44 pin adaptor.

I can even access the entire 6GB of space, so it will do nicely for now!

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