Hi Everyone,

since i stumbled across this forum a few times in the last couple of days and some posts have helped me a good deal with my recent project, i thought i might post here myself because i'm pretty much out of ideas.

here's the story:

an IBM 5170 appeared at my door a couple of weeks ago and after some smelly smoke, repairs and upgrades, i got it to an almost useable state now - there's only one more thing before i can close that big old metal case and call it done.

i have replaced the preinstalled hercules video card and the floppy + mfm controller board with a vga card and floppy + ide controller because i intend to use two 8mb CF cards i have left over from old cameras as fixed disks instead of the noisy and potentially failing full height MFM hard disk. 8mb might sound laughable by todays standards but i've recreated the planned setup in PCEM and found that 8mb should be just enough to install dos 6.22 (or dos 5.0 + win 3.0 and maybe norton commander 4 if you squeeze hard enough)

i also added a 3,5" 1.44mb floppy drive to the single 5.25" 1.2mb drive that was already installed

i learned that this machine is an early model with a slow 6 MHz 286 + 287 on a type I mainboard with 2 BIOS ROM chips, wich i replaced with an AMI bios because the IBM bios is a pain to set up without the diagnostics diskette (wich i don't have)

this AMI bios allowed me to boot off the 1.44mb floppy and set the proper C/H/S parameters for the CF cards to be used as HDDs ...

DOS (booted from a floppy) can see, partition, format, write and read both cards and install itself onto it but the computer is not able to boot from them for whatever reason.

i have tried a different IDE controller and a 128mb DOM instead of the CF cards with the same results.

i have tried "fdisk /mbr" as well as installing the DOM into a newer computer to zero out the MBR manually using "dd" from a linux usb stick.

when i did this, i was a bit too slow to press F11 to get into that computers boot menu where i could select to boot from usb, so it tried to boot straight off the DOM and it worked - DOS 6.22, wich i had installed on the DOM when it was in the 286, started right up - so there was nothing wrong with the installation or the media itself.

i had read that this seems to be a known issue on old computers and the solution would be to install a compatible version of the XTIDE/ATIDE/386IDE universal bios either by buying the XTIDE controller card with an eeprom included, or flash it to an eprom yourself and use it in a network card with a rom socket.

since i had some more of these 32k eproms (intel D27256) on hand that i used to get the AMI bios into the machine, i had already prepared another eprom with the ATIDE bios (i used atidel.bin 'cause it's an AT machine, not an XT) and put it on a network card.

i used a 3com etherlink III that i had configured to use 32k roms chips and map the ROM to adress D000h - but the AMI bios just booted like it always did and threw the usual error about no bootable drive, as if the ATIDE bios wasn't there at all.
then i ran CheckIt and it detected a 16k ROM at D000h-D400h that wasn't there previously - so the 3com card seems to be doing what it's supposed to.

i shut the machine down and put the original IBM bios rom chips back on the mainboard, and unlike the AMI bios that just acted as if nothing had changed, the IBM bios reported a bad rom at D000h.

erasing the eprom, then burning and verifying it again did not change anything, trying another network card (SMC 1660BT, again set to D000h) did not do anything either.

my only other computer with isa slots is a pentium III, so i testet both cards with the ATIDE and 386IDE ROM in there but nothing happens there either.

i am out of ideas and THIS close to pulling my hair out, (what little hair i have left to pull anyways)

what am i doing wrong?