Thought I'd resurrect this thread so I could add my experience.
I have a Promise Ultra 100 TX2 that I recently upgraded to the newest bios from the Promise website. Before I upgraded the bios on the controller, I had a very old firmware version. Had the same behavior with the old firmware too, which is why I upgraded it.
I have several socket 7 boards. When I put the Promise Ultra 100 TX2 in a Socket 7 board, it detects drives on bootup and installs its bios and works OK in Win98se, even with the onboard IDE enabled. Works with a quantum fireball ex, SD2IDE drive, CF adapter, and a hyperdisk DOM.
I have two Socket3 486 boards with PCI slots , FIC VIP (old Via chipset, no integrated IDE controller) & Gateway BAT4IP3 (i420EX chipset, integrated IDE controller). Both are using AM5x86 chips, no overclock. One has WB enabled, the other is WT.
When I put the Promise controller in either of the socket 3 boards, it does not detect any of the drives at boot, does not install its bios, and does not show any drives in Win98se. Same drives & cables & power supply as I used in the Socket 7 boards. Only trying one drive at a time, jumpered as master. Same behavior with another IDE controller enabled or not. Completely vanilla Win98se, no service packs, install using the same automated install script as the Socket 7 boards, using the same out of box VGA driver and the latest Promise IDE driver from the Promise Website.
My guess is the root issue happens during boot up when the Promise controller fails to detect the drives.
What part of the 486 systems could be affecting the Promise Ultra 100 TX2 drive detection?
I guess I could try an older 486 CPU instead of the AM5x86 chips, but I hate to mess with all of the voltage stuff again.