Lzone and Precomp aren't necessary, provide information about the motherboard and the BIOS version.

Lzone and precomp are NA for that drive, as it is IDE and should never be low level formatted/does that internally, and autoparks its heads on poweroff.

To make the cmos happy, set them to 0 for precomp, and 65535 for Lzone.

If it doesnt take, check the drive's health.

Do you have another retro build that ranges between 430FX Triton (the first Intel chipset with integrated IDE controller) and the last batch of non-UEFI BIOS with at least one PATA connector? Most MB in this vintage range had BIOS that could autodetect parameters of any IDE HDD.

BTW, many thanks to this thread that helps me finding the MB of my very first PC: DTK PEM-2035

retropc5x86 wrote on 2024-07-18, 02:54:

It came with an 89MB ST-1102A, and since none of the preset Disk Types matched I tried setting up a User one to no success.

What does "no success" and "wouldn't work" mean, exactly? BIOS refuses to accept the values or what?

Precomp(ensation) is irrelevant for IDE/ATA HDDs, any value here should therefore "work". Landing zone is not used by BIOS anyway, it's only stored so that programs that park HDD heads would know where to seek. So this too should accept any value up to 1023. Usually it's the last cylinder or +1.

There are some early BIOSes that don't accept user values, type 47 can't be edited at all. Might be all zeros, might be predefined to something. If that's the case and you can't find an alternative BIOS that allows to set this you are limited to two options:
- Using predefined BIOS settings that match your HDD best - you want sectors and heads to match exactly, and the cylider count to be less or equal what your HDD has. Cylinder count can be greater too but only if you are able to edit partition data yourself (using Norton Utilities for example). That would work but will confuse programs like NDD or SCANDISK. NDD at least allows to ignore it.
- Install a software overlay or better yet use XTIDE BIOS extension in a network card as carrier. That will let you completly ignore BIOS HDD settings. This has the added bonus of supporting HDDs > 1023 cylinders on these mobos.

Thanks for everyone's suggestions. I know LZ and Precomp aren't nececessary for IDE but setup seems to require them nonetheless.

@wierd_w setup will take 65535 for precomp but not for lzone

@dormcat I tried an ST3491A in a super socket 7 mobo and had it detected as 899cyl, 15hd, 62sec, 65535precomp 898lz but even after entering those values in the PEM-2530's setup the HDD wasn't detectected.

@Deunan what I mean by no success is that setup will let me input the values and set the "user type" for the hdd, but once booting through a floppy, fdisk won't be able to detect the disk. No matter what combination of values I enter for precomp/lz, fdisk won't find the hdd. And I'm using a known-working one.

I think the BIOS might only be compatible with MFM/RLL and not IDE since all the predefined hdd types do have Precomp and LZ values and all have 17 sectors. Also, the original user manual for the PC doesn't mention "IDE" at all.
I don't have any MFM/RLL disks to try, so I guess next in line is to try XT-IDE once I manage to erase one of my EPROMS.

Sorry for the delayed response y'all. Work got intense.

retropc5x86 wrote on 2024-07-27, 21:39:

I think the BIOS might only be compatible with MFM/RLL and not IDE since all the predefined hdd types do have Precomp and LZ values and all have 17 sectors. Also, the original user manual for the PC doesn't mention "IDE" at all.
I don't have any MFM/RLL disks to try, so I guess next in line is to try XT-IDE once I manage to erase one of my EPROMS.

An AT compatible BIOS should not care whether the drive is MFM or IDE as the controllers use the same port address and interrupt. From its point of view the hard drive is just an ST-506/412 compatible interface, the main difference being that the control circuitry is in the controller card for MFM and integrated to the drive in the case of IDE (hence the name "Integrated Drive Electronics").

So as long as you input values for cylinders, heads and sectors per track that are equal or less than those of the HDD you're using it should work, in the case of IDE devices the LANDZ and PRECOMP values will be ignored as they have no effect.

For instance, my DTK PTM-1630 has a BIOS with the same limitations (no custom User type available for HDD) and yet an ST-157A IDE HDD works perfectly with type 14.

retropc5x86 wrote on 2024-07-27, 21:39:

@dormcat I tried an ST3491A in a super socket 7 mobo and had it detected as 899cyl, 15hd, 62sec, 65535precomp 898lz but even after entering those values in the PEM-2530's setup the HDD wasn't detectected.

The first three numbers match Seagate's suggestion in its manual. The reason why it was not detected, however, is beyond me.

Have you tried ST-1102A instead? Its smaller size might have better compatibility with the old BIOS. The manual suggested 17 sectors/track, 1024 cylinders, and 10 heads.

retropc5x86 wrote on 2024-07-27, 21:39:

I think the BIOS might only be compatible with MFM/RLL and not IDE since all the predefined hdd types do have Precomp and LZ values and all have 17 sectors. Also, the original user manual for the PC doesn't mention "IDE" at all.

Very unlikely, as the HDD that came with my aforementioned PEM-2035 was a Seagate ST-157A with IDE interface. Your KEEN-2530 was slightly newer than mine.

retropc5x86 wrote on 2024-07-27, 21:39:

@Deunan what I mean by no success is that setup will let me input the values and set the "user type" for the hdd, but once booting through a floppy, fdisk won't be able to detect the disk. No matter what combination of values I enter for precomp/lz, fdisk won't find the hdd. And I'm using a known-working one.

Bad IDE cable perhaps? Some of these develop oxidation or corrosion on the connectors (depending on storage conditions). Try a different one. Boot from floppy and try a program (HWiNFO, NSSI, whatever fits on the floppy) that detects IDE devices by scanning the ports directly. See if those detect the HDD at all.

Deunan wrote on 2024-07-28, 11:31:

Bad IDE cable perhaps? Some of these develop oxidation or corrosion on the connectors (depending on storage conditions). Try a different one. Boot from floppy and try a program (HWiNFO, NSSI, whatever fits on the floppy) that detects IDE devices by scanning the ports directly. See if those detect the HDD at all.

Lo and behold... it turned out to be a faulty IDE cable. I can't believe I hadn't considered it. I got so fixated on the Precomp and LZ values I forgot to do the basics.

Thanks everyone for your suggestions. I greatly appreciate your input and now have a better understanding of how an IDE HDD interfaces with the BIOS/Setup.

Now that the PC is up and running, feel free to ask for any info about it.

Thanks again y'all!