First post, by CelGen
I put together an ASUS ISA-486SV2 Rev. 3.1 motherboard with a Trident VLB video card, PRIME 2 chipset disk and I/O ISA controller with a 66mhz DX2 and I can't make it work with the floppy drives. Put a bootable floppy in and while it will light the drive and spin the motor it will just sit there with DISK BOOT FAILURE.
The PSU, CPU, ram, cards, cabling and the floppy drives were tested on a different 486 board and all verified to be working. Even used all the hardware to install DOS onto a DOM with no read or write issues.
Swapped the ASUS board back in, booted to the DOM and then tried to read from either floppy drive and still all I was getting was an activity light, spinning motor and DATA ERROR READING DRIVE x. Threw ram, cache and CPU benchmarks at it to quickly verify it wasn't a borderline part to no avail. Went into the BIOS, defaulted everything and turned off video BIOS caching plus the internal and external CPU caches. Still nothing. I've gone through five other I/O and disk controllers and tried using a more generic ISA VGA card and they all do the same: Work fine on the test board but no floppy on the ASUS. That I can tell from https://www.elhvb.com/webhq/models/486vlb2/486sv231.htm I think the motherboard is jumpered correctly with no battery damage.
"It's science. I ain't gotta explain sh*t"