29 Jun
2000
29 Jun
'00
2:21 p.m.
The problem with (1970's) IBM machines as against
similar vintage DEC
machines is that the IBM machines have a lot less 'hacker' documentation
available. For some IBM systems it can even be hard to get the binary
opcode list, something that DEC have been known to stick in the
advertising flyer.
DEC machines generally had at least schematics and a technical manual
available. And most of the components were off-the-shelf. This, alas,
doesn't apply to IBM machines.
Certainly many of the old IBMs could be hacked with (if the shop would
let 'em - probably more of an issue!). The only machine I can think of
that was really a mystery back then was the S/38, because it was so high
level (S/38s somewhat mutated into the AS/400 family). Lots of
information - enough to do some darn cool hacks - was commonly available
for the S/360 and S/370, S/3, S/32,34,36, and S/1 (basically most of the
biggies of the 70s and 80s).
Hardware and maintenance docs for the old systems used to be very locked
up, but not anymore. Many of the machines that are popping up these days
have the set of Big Blue Binders with them, as apparently IBM is not
taking them back anymore (or is not too careful about it). Once the rhyme
and reason is solved behind the organization of the maintenance libraries,
the machines get described in minute detail - actually far better than
DEC docs.
William Donzelli
aw288(a)osfn.org