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486 Olivetti - BIOS/CMOS seems to be a DOS program that runs from HDD???

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First post, by Tmp2k

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I have an Olivetti PCS/44, luckily it's got the original HDD and backup floppies. The backup battery had died so it wouldn't recognise the HDD to boot DOS. However, I did notice that when I went into BIOS (CMOS config) the HDD burst into life and started chuntering whenever I changed menus etc.

I soldered a modern battery holder on the mobo and after some experimenting, I found that setting "Hard Drive 1" to "High Capacity" allowed it to boot into DOS. The harddrive setting can be either "Standard" "High Capacity" or "None Standard" the latter allows you to manually enter CHS settings.

I've also have a "User Diskette" which is basically an MS-DOS boot disk with all the BIOS programs on it. You can boot from this disk and it has the same result as entering BIOS setup.

So here's the thing... I've put the HDD in another machine and it only reports 1 partition, I can't find the BIOS programs on it anywhere. I've also reinstalled DOS/Windows and formatted and it's not affected it. But if I don't plug that HDD into the machine, I cannot get it to enter bios setup, unless I boot from the User Diskette. Entering BIOS from the HDD does not involve booting, you press Ctrl+Alt+U and it jumps into BIOS, whereas the User Diskette is like a regular DOS boot disk. So it's like there's a copy of the User Diskette hidden on the HDD somewhere. Also it still goes into BIOS even if the HDD isn't configured correctly and the machine can't boot to DOS.

I've tried swapping the HDD and even when manually entering the CHS setting in BIOS the machine just doesn't seem to like any of the other HDDs. I'm also worried that when I swap out the HDD I'll lose the ability to enter BIOS without the User Diskette, and then what happens if the Diskette fails 😖 (I know I can make a copy etc) But I'd rather not have to use a floppy disk just to get into BIOS.

I've now started getting the occasional HDD related error so I'm worried the current HDD is on it's way out anyway.

Does anyone have any experience with this kind of BIOS system and actually knows what's doing on here? How can I swap out my HDD and keep the ability to run the BIOS config without using a boot floppy?

Reply 1 of 3, by Jo22

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Tmp2k wrote:

Does anyone have any experience with this kind of BIOS system and actually knows what's doing on here?
How can I swap out my HDD and keep the ability to run the BIOS config without using a boot floppy?

This reminds me of Compaq computers and the IBM PC/AT. While the BIOS was in ROM, the CMOS Utility was not.
I believe, if you have the user diskette, you likely can re-create such a hidden partition (like on a Compaq machine).
If you haven't, you can still try to make a 1:1 copy of that HDD - either to an image file or to another HDD.

Programs such as Acronis True Image* -for example-can do a sector-based copy, instead of a file-based copy.
They usually default to that method, if no known filesystem is found, for example.

These programs require a more modern computer (Pentium or Pentium II), of course
(Acronis TruImage live media used to imclude a DOS-based version, too.).

(*I was using version 7 to 10)

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 2 of 3, by ppsh41

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Tmp2k wrote:

I've tried swapping the HDD and even when manually entering the CHS setting in BIOS the machine just doesn't seem to like any of the other HDDs. I'm also worried that when I swap out the HDD I'll lose the ability to enter BIOS without the User Diskette, and then what happens if the Diskette fails 😖 (I know I can make a copy etc) But I'd rather not have to use a floppy disk just to get into BIOS.

I have a PCS 44/C, in my case I can re-create the hidden partition on the HD (called "System Region") booting from the User Disk. There is an option, somewhere, to do this on new HDs.

Try to navigate in the menu or check the various .exe files (I don't rememeber exactly where is it)

PS: just landend on this awesome board! 😀

Reply 3 of 3, by Tmp2k

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Jo22 wrote:

If you haven't, you can still try to make a 1:1 copy of that HDD - either to an image file or to another HDD.

Yeah I had the same thought, I have an image of the HDD but I can't see any additional partitions and I'm fairly familiar with MBRs and partition tables, so I have literally no idea where the config files are being stored. Putting this image onto another HDD didn't work either because I can't get it to recognise any other HDDs despite putting the CHS settings in manually.

ppsh41 wrote:

I have a PCS 44/C, in my case I can re-create the hidden partition on the HD (called "System Region") booting from the User Disk. There is an option, somewhere, to do this on new HDs.

Try to navigate in the menu or check the various .exe files (I don't remember exactly where is it)

I've checked the user diskette menu and there's no option to copy anything back to the HDD. I'll have a look see if there's any other EXEs. I've also just noticed that the user diskette has less options on the menu. The version on the HDD includes diagnostics etc. So I'm also thinking there's not enough room on a floppy to fit all the files 🙁

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