The bios needs to match the board

An XTIDE rom in a cheap network card would get you round the bios limitation

squelch41 wrote on 2020-08-09, 12:19:

The bios needs to match the board

An XTIDE rom in a cheap network card would get you round the bios limitation

Thank you Squelch41, I'd heard of XTIDE for older XT systems but never considered it's use on a 486 era computer. I will search for an XTIDE BIOS and appropriate network card that can utilise the BIOS. I have to give the designer of that credit, using an Ethernet (or I suppose you could also use a SCSI card) to modify the bios is pretty clever.

And if you have trouble with XTIDE for any reason, don't forget about translation software like OnTrack or EZ-Drive; it wasn't clear if you know about these.
For the drive sizes you specify there shouldn't be any trouble with the BIOS handling them. What could be missing is a workaround for a dumb limitation with the interface the BIOS exposes to DOS.
IDE drives can have 16,383 cylinders, but only 16 heads. The BIOS interface can have 255 heads, but only 1024 cylinders.
For > 504 MB drives (the limit comes from 1024*16*63*512/1048576) your BIOS has to do some bit twiddling with the cylinder-head-sectors between the drive and DOS to make it look like the drive has fewer cylinders and more heads.
The best case scenario is "LBA", where how to do so is standardized.
Older BIOSes have things called ECHS or LARGE, where it's specific to each BIOS company and the drive may not be partitioned correctly if moved to another machine.
If the BIOS supports none of these, then what OnTrack or EZ-Drive do is put a piece of software in the first 504MB of the drive that replaces the BIOS routines with their own that access the hardware directly and do the translation.
BTW, if you end up running Windows 3.x, you deal with this issue over again to get 32-bit disk access. Look at MH32BIT.

If you're feeling curious, you can connect one of those big drives to the machine, configure it in the BIOS, and boot from a dos boot floppy that has the debug command on it. We can give you some commands to type in to pull some information from the BIOS to see whether it is doing the translation or not.

Hello Jake,

I don't recall seeing any options in the BIOS which would imply large disk support. I can't even see an option to manually set cylinders/tracks/heads, the BIOS allows selection from a list or auto detect. Although I'd be surprised if the BIOS has large disk support I would be interested in seeing if the BIOS is doing the translation or not. At present I don't have the larger disk to put in the computer, but I'm sure I have an 80GB IDE drive somewhere if that would be useful for the test, hopefully it's not too modern.

I wasn't aware of OnTrack or EZ-Drive, it's very useful to know that there are software solutions as well as hardware, if I was to go the software route I would have to use MH32BIT as well; the computer is mostly for DOS based software but I do have WFW 3.11 installed for nostalgia and a few Windows based games.

Many thanks for your help
Jim

Just a quick update:

I bought a 3.2GB WD Caviar drive, although a little modern for the computer it's going in I have used EZ Drive to create a 2GB partition for drive C and a 1.2GB partition for drive D. All appears to be working well on it.

Thank you both for your help, it is much appreciated.

Hi thevdm!

Would you mind to make picture of the CN1, CN9, CN10 connectos with cables attached? Unfortuantely these connectors are not documented. I have the same board, disassembled for testing. I made pictures about this part of the board before disconencted the power led, the ide led and the speaker but unfortubately the pictures gone with the phone. It would be a great help! Thank you in advance!