What happens if I can't find an HD type in old BIOS and I am not given the option to manually type values or autodetect? \ VOGONS

What happens if I can't find an HD type in old BIOS and I am not given the option to manually type values or autodetect?

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First post, by Optimus

Posted on 2022-02-16, 10:35

Optimus Offline

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I recently got a very old motherboard with 386SX and a BIOS called NEAT. I haven't seen this BIOS before.

The problem is that when I try to setup a HD, there are only specific TYPES from 1 to 45 with specific Cylinders/Heads/Sectors/etc..
I am used to other BIOSes (like AMI BIOS for example) where you would either given the option to manually type the values, or simply automatically detect.
But this one doesn't seem to have this option. The only thing I can see is a TYPE 15 where all values are 0,0,0,0,0 (is this some type for autodetect? It didn't seem to work with one HD I tried).

What happens with this? Also,. if I have an old HD that matches few values (like Cylinders or Heads or both) will that work? Which of these values are the most essential? I wrote down on paper all the types and values to be able to compare. There are even values like PRE-COMP and LAND ZONE which I don't even know how important they are.

p.s. I even tried my XT-IDE that takes CF card and was even working on my 8086 and a 286. On this 386sx it simply doesn't work, the boot freezes at some point. I wonder if I could use some of my other more modern CF cards I use on later PCs (with 512MB CD cards) that are autodetected on their BIOSes, but what would be the values for the old BIOS to even work? I don't know how CF cards work with this Cylinder/Head/Sector paradigm (many times some of them display wrong things) when it's not a real HD. I had issues even on 386dx/486/Pentium sometimes, so I didn't even dare to try on this 386sx (and what should I type for them if I could manually?)

Reply 1 of 6, by appiah4

Posted on 2022-02-16, 10:54

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I'd pick a type vith CHS values as close to the one you have, where each value is lower. You won't have all the capacity but it will likely work.

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Reply 2 of 6, by konc

Posted on 2022-02-16, 11:36

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The common way to deal with this back in the days was using some dynamic drive overlay (DDO) software.

Reply 3 of 6, by Grzyb

Posted on 2022-02-16, 13:01

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PRE-COMP is irrelevant for IDE drives.
Same for LAND ZONE, unless you have one of those very early drives, with stepper, not larger than 80 MB or thereabouts.

Only CHS values matter - as already stated, make sure that neither of them is greater than actual.

Nie tylko, jak widzicie, w tym trudność, że nie zdołacie wejść na moją górę, lecz i w tym, że ja do was cały zejść nie mogę, gdyż schodząc, gubię po drodze to, co miałem donieść.

Reply 4 of 6, by Deunan

Posted on 2022-02-16, 15:07

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Optimus wrote on 2022-02-16, 10:35:

p.s. I even tried my XT-IDE that takes CF card and was even working on my 8086 and a 286. On this 386sx it simply doesn't work, the boot freezes at some point.

Does this system boot with HDD set to none but the CF card connected? Some motherboards apparently do not tolerate none setting when something is indeed connected. But if it does boot then try none with XT-IDE which has its own detection code. In general I found that some controllers and CF card combos do not work, and perhaps an old BIOS adds another layer of issues on top of that. So you might just have unlucky combination, if you have other parts to try please do.

If you can boot the system from floppy and then run NSSI, HWiNFO or some other app that will detect and report the IDE devices, see what they claim to be. I found that CF cards (usually for industrial use) that lie and pretend to be non-removable magnetic type media work way better than the CF telling the truth about being removable or non-magnetic. This might help you pick a better card for this system.

Reply 5 of 6, by Optimus

Posted on 2022-02-16, 15:39

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Thanks, there are a lot of good suggestions, I'll try things this evening.

Reply 6 of 6, by Jo22

Posted on 2022-02-16, 16:16

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Grzyb wrote on 2022-02-16, 13:01:

Only CHS values matter - as already stated, make sure that neither of them is greater than actual.

I second that.

Back in the 90s, I was an user of a 286 system and the Setup Utility didn't feature user defineable settings (no type 47).

My father and me thus selected a fixed-disk entry (40MB) from the chart that was within the limitations of the 80MB Conner drive.

@Optimus That being said.. If your HDD is kind of intelligent, and has some sort of internal sector translation mechanism,
you can use phantasy values.
However, these must not exceed the actual drive capacity. 😀

And please never use low-level format in Setup Utility on IDE/AT-Bus drives.
At best, nothing happens. At worst, the drive gets confused/messed up.

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