On 3/3/2017 1:08 PM, Fred Cisin via cctalk wrote:
On Fri, 3 Mar 2017, Jules Richardson via cctalk wrote:
Just checking here, as someone told me that this is the case, but do
the Compaq Portable 286 and Portable III take stock 40-pin IDE hard
drives? I just wanted to make sure that they weren't expecting
something that might be a bit non-standard before I go trying to find
modern replacements for a pair of failing disks.
I think so, but I also think that Compaq's IDE was before it was
completely standardized, so there might be some glitches.
The bios has a table that you can dump out as usual, which is unique to
the Compaq portable 3. Other than that and having to modify the table
to accommodate the new drive geometry, I had no problem. It was
possible to run 200mb drives, as all of min have such on them.
Assuming that an enormous modern(ish) drive is OK, are there any
other gotchas involved in configuration and formatting? Obviously I
don't need a partition bigger than a few tens of MB, but perhaps
there are things to keep in mind when fitting a drive that's most
likely to be getting on for a thousand times the capacity of the
original.
1) If you are going period OS, get Compaq MS-DOS V3.31. Anything
prior to that is limited to 32MB per partition.
2) You may want to use a "disk manager overlay" to be able to use
specs other than the BIOS ones:
http://www.seasip.info/VintagePC/compaq3.htm
I ran Pick and other systems other than DOS and modified the roms to
have new geometry. The entries up to #13 match the IBM.
I think #4 and #20, IIRC are the common ones you see as evidenced by a
sticker on the case behind the plasma display.
The Roms are simple to modify, if you know that they are Even / Odd for
a 16 bit total width. you will have to figure out a new checksum and
modify the last byte of the rom to come up 0. Again, if i recall you
need to make the overall sum come up = 0.
I always read the rom from high memory into ram and wrote a simple loop
to add up the checksum in AL. The play with the last byte till you get
it back to 0.
I ran Pick R83 on all of mine, with an 8way and streaming tape card in
the expansion bay. A very nifty 286 or 386 8 user system for demos back
in the days
thanks
jim
