20 Jul
2014
20 Jul
'14
4:49 p.m.
I managed to find a bios for an IBM 5170 AT 286 Type1 Mainboard. It is
here: 30aprile1989 (list here:
http://ibm-pc.org/firmware/ibm/5170/5170.htm)
In practice I have manually added the number of cylinders, heads, and sect
/ trk that allow the machine to recognise a disk IBM 250MB. At this point
regularly boots DOS.
But I wish to program these data permanently in the bios. Does anyone know
what program to use and give me the procedure? I tried with BIOSUTL, but
the new EPROM do not boot the machine.
When I did this, I used a couple of 8Kbyte EPROMs and fitted them into
the spare sockets on the motehrboard. I then added a bit more logic (I
think just one IC) to disanble the top 8K words of the origian BIOS ROMs
and enable the extra EPROMs. This was relatively easy, since the enable
lines are o nthe DIP shunt at the rear edge of the motherboard.
There was no real reason to do this, it just meant I could use 2764s from
my junk box, whereas I would have had to order the 27256s.
I didn't bother with any program other than a hex editor. I simply
editied the values in the ROM image, recalculated the checksum (OK, I
think I wrote a program for that), then took the last 8K words of the new
image, split them into odd and even bytes, then programmed the ERPOMs. I
had no trouble at all.
-tony