@devius

Sorry for being late. Had to take care of some things yesterday and i could not take the 286 for a ride.

It was actually F2 the key i was pressing to go into setup and not Supr (del). I´ve attached two shots of the bios version and the options i can choose in it. Im not using a Hard disk right now, had some problems with the one i was using and Ontrack disk manager... i should take some free time out of work and actually test an IDE to CF in this machine.

Really hope you find this useful.
Keep going! Regards!.

Can you please dump the BIOS? V2.03 seems not be dumped so far.

derSammler wrote:

Can you please dump the BIOS? V2.03 seems not be dumped so far.

I´d be glad to, but i dont have an Eeprom reader right now. If you can point me to any soft utility that would let me read it and store it safely on a floppy, i´d try to do it in january or as soon as possible.

All you need is MS-DOS, it comes with debug.exe which can be used to dump the BIOS:

http://mess.redump.net/dumping/dump_bios_using_debug

Drivers/Software/Manuals: https://forum.classic-computing.de/forum/inde … strad/&pageNo=1
Biosdump/Bioses: https://forum.classic-computing.de/forum/inde … 90764#post90764

Turns out I was overthinking it. I put the dummy resistor back in, connected the PSU to the PC and everything worked fine:

So, in short, all it took was replacing the TDA4605 with a new TDA4605-2 and R3 with a new 1W resistor of the same value. The original one was 1/4W but that is not enough for a resistor that is connected directly to the mains. I also replaced all caps for good measure.

Next problem: one of the floppy drives is missing, so I need to retrofit a standard floppy disk drive to the proprietary connector used in this PC. Either that or get some kind of cover for one of the empty floppy drive slot.

Almost done with the restoration. I replaced the rechargeable battery with a new one and now the BIOS settings are saved correctly.

However now I can't for the life of me get into the BIOS setup again. I tried F1, F2, F10, Del, Enter, Ctrl and so far nothing. What I do is tapping the key repeatedly after pressing the Reset switch until it starts beeping. It never works. Always counts the RAM and boots straight to DOS as if nothing happened.

Previously when the battery was dead it would not save the settings if I powered down the PC, so it presented the option of pressing F2 to enter the setup on the next boot, but now I can't count on that any more.

Can anyone explain what is the exact procedure to get into the BIOS Setup?

I don't remember ever having had issues getting to the BIOS screen on my two Schneider Tower ATs. However, I can't say which key to press - it's been a while...

In many cases however I use a trick when not knowing how to enter the BIOS: hold down the left shift key. Unlike other keys, this will not flood the buffer but still causes a "keyboard stuck" error, which should give you the option to either continue or to enter the BIOS.

Thanks for the tip, but unfortunately it didn't work. It just boots normally but bypasses config.sys and autoexec.bat.

I tried start tapping the keys after the memory finishes counting, but that also did nothing. I also tried tapping at a slower rate.

I wonder if it could be one of the jumpers that is configured to not allow entering the BIOS setup or something, but I'm a bit scared of changing them since there's no labels on what they do.

Hi, what happens if no keyboard is connected ?
On some PCs, this should trigger a warning message ("keyboard not present" or similar) with an option to enter Setup.
(That, of course, only makes sense if the keyboard is connected again once the warning is displayed.)

Yeah, I also thought of that, but by default the BIOS was configured to not halt on keyboard errors and I didn't think it was necessary to change that, so it will only halt on Video errors now, but the graphics card is built-in so there's no way to trigger that particular error.

devius wrote on 2019-12-30, 19:29:

but by default the BIOS was configured to not halt on keyboard errors

Ok, that also explains why holding the shift key does not work. You need to disconnect the CMOS battery in that case to get access to the BIOS again.

Jo22 wrote on 2019-12-30, 18:44:

(That, of course, only makes sense if the keyboard is connected again once the warning is displayed.)

Which would most likely blow the fuse, as a PC/AT keyboard should not be connected when powered. Doing so can even destroy the keyboard controller.

Ok, I was able to get into the BIOS setup by removing the floppy drive cable since it was configured to also halt on floppy errors. I enabled stopping on keyboard errors, so now I'm able to get into the setup by using the trick of holding down the Shift key. I would still like to know how to do it normally though.

The battery is soldered down, so it would have been a pain to remove it.

So, I got everything working and I even installed a Sound Blaster 16 and got it to work, but I'd really like to replace the original HDD with a CF card, since the HDD is absurdly loud and is only 44MB.

I tried connecting the CF adapter directly but with a 512MB card the PC won't even boot. The keyboard LEDs stay on and the screen doesn't come up, which seems to indicate that some kind of basic initial process is failing. It's not reversed cable since I also tested that possibility. With a 2GB card the PC does boot up but it always says "Disk controller error" even after manually typing in the correct CHS values into the BIOS.

I'll have to try with a smaller card (I don't have any at hand at the moment) before I try to go the XTIDE Universal BIOS route, since I'm not sure how to achieve that. Would I need one of those XT-IDE 8-bit controllers?

devius wrote on 2020-01-12, 17:24:

I'll have to try with a smaller card (I don't have any at hand at the moment) before I try to go the XTIDE Universal BIOS route, since I'm not sure how to achieve that. Would I need one of those XT-IDE 8-bit controllers?

Try with a disk manager. I managed to get mine going (512 one, with multiple partitions) with this one recommended by phil https://www.philscomputerlab.com/ontrack-disk-manager.html, but i had to pre-format it on fat16 on another pc BEFORE doing anything with it on the 286 or it would just be ignored by the system.

XT-ide will make it a lot easier and problem free, but is a bit pricey if you dont have a card that you can overwrite and have to buy one.

Emu10k1 wrote on 2020-01-13, 10:03:

XT-ide will make it a lot easier and problem free, but is a bit pricey if you dont have a card that you can overwrite and have to buy one.

Pricey? If the system has IDE already (which it has), all you need to do is to write the XT-IDE BIOS onto an EPROM and put that onto a LAN card.

Anyway, you can not use a CF card or hard disk larger than 504 MB, as the BIOS can't handle that. If you try to use a larger card, you'll have one of the two problems:
1. you enter the correct CHS value, which the BIOS can't handle and most likely freeze during POST
2. you enter wrong values within the 504 MB limit, causing a hard disk controller error message

With some luck, you can get around 2 depending on the values you enter. Then you could install a disk manager to fully use the capacity. However, just using the XT-IDE BIOS is a much better idea.

As with my Schneiders, I kept one original with the 44 MB MFM drive, and the other one got SCSI.

derSammler wrote on 2020-01-13, 12:49:

Emu10k1 wrote on 2020-01-13, 10:03:

XT-ide will make it a lot easier and problem free, but is a bit pricey if you dont have a card that you can overwrite and have to buy one.

Pricey? If the system has IDE already (which it has), all you need to do is to write the XT-IDE BIOS onto an EPROM and put that onto a LAN card.

Pricey as if he doesnt has a card already to overwrite, he either needs to buy one or needs to buy a kit (or a premade one), and the kit is going around 45-50 euros easily. Note that he is asking if he needs to use/buy one of the "XT-IDE 8-bit controllers" as in "the Kits Lo-tech and the like is selling". Yeah, he could chase a lan card for 15 or 20 in ebay o something, but lately they have been scarce if he really needs it to be an 8bit one.

Well, I can indeed use a LAN card, as I still have a couple unused ISA ones and one of them has a free ROM socket. I'm going to try to see if I have a EEPROM chip that I can salvage, otherwise that is something that I need to buy. I remember reading about a generic ROM writer program that can work with a vast array of host cards, so I should be good there.

I'm also fine with just using a smaller CF card if that works, which is something that I have yet to test.

I was finally able to test the PC with a 256MB Compact Flash card and it detected the card and is able to access it just fine. I'm perfectly OK with this capacity so I'll just order a new 256MB card since unfortunately this one is already being used in another PC.

When that new card arrives I'll be able to finally finish this process.

That took way longer than expected, but I finally finished it thanks to the new 256MB card.

I ordered 3 cards but only the Cisco one worked properly. The others would always hang at 98% when installing DOS 5.0, and even installing on a VM and using dd to write the raw image to the cards wasn't working. I could see the files and boot fine from a floppy disk, but when trying to boot from the card it always complained that the disk was not bootable.

I also upgraded the RAM to a whopping 2MB!!!

Here's the result from the outside:

It has a few scrape marks, but they're clean now so not as noticeable. And the insides:

I'm very happy with the result! The PC works and looks great now. 😃