IBM PC bios source available

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Mon Mar 10 22:36:00 2003

On Mon, 10 Mar 2003, Steve Thatcher wrote:
> Hi all, I don't know if anyone is doing anything with the original
> PC, but when I had mine I converted it to an XT with a 15meg
> hard drive. I ended up typing in the PC monitor and modifying
> it so the bios had a drive entry for the hard drive I had purchased
> (actually I bought a 10meg and they gave me a 15meg instead).
> I have a zip file that has both the orginal source and my modified
> copy if anyone is interested. Just email my privately and I will
> pass the ZIP on.

The original XT hard disk controller (Xebec) could handle certain
geometries of 5, 10, 15, 25 MB with a trivial hardware mod. NO software
changes required.

Near the center of the board are eight solder pads. If you install a dip
switch there, you get 4 different drive types for each of the two
drives. Both off, the default, is 10 meg (306 cylinders, 4 heads).

But, if you wanted some other geometry, (or were unable to solder a switch
or jumpers on, then you needed to do some patching, preferably to the ROM
on the controller card.
Received on Mon Mar 10 2003 - 22:36:00 GMT