I finally got up the nerve to do it, and my free space went from
696,320 to 1,024,000 -- a gain of 327,680, or nearly 50%; not bad for fifteen
minutes' hacking.
The instructions are in one of the postings by Douglas Brantley and/or Brian,
in one of the collected works (I forget which volume). I only had two
problems: I wasn't sure whether to use decimal or hex offsets, and I forgot to
make myself a bootable floppy before I started. The first one is probably
documented, but I hadn't printed out a copy, and was going by some scribbled
notes; at any rate, I figured it out by looking at the appropriate locations
and matching the advertised contents (answer: decimal offsets). As for the
bootable, make sure you have one. I was able to boot off an old disk that I
had for another system, but it must have caused some sort of problem with the
format of c:, and I had to do the whole thing over again.
REMEMBER TO BACK UP C: BEFORE YOU START, but there is really no excuse for not
taking the plunge, and lots of KB to gain. I used 02 at offset 13, and 08 at
offset 22, BTW.
P.S. If the Mac extension cord is straight through, could someone with some
electronics background explain why it would be dangerous to try using it as
a power-cable extender?