On Tue, 20 May 2025, Bill Gunshannon via cctalk wrote:
I just managed to score a 5155. Well, soon, it is waiting for me to
pick it up at the University where I used to work. It looks to be in
really good shape and has been in storage for probably two decades or
more.
A couple quick question for anyone familiar with this system.
Is it likely there is one of those little batteries on it that would
now be dead and need replacing before I try to use it?
It is a 5160 (IBM PC/XT) is a different case. Luggable, like an original
Compaq, although most people feel that Compaq did a better job of
converting to a aluggable, specifically including how much of how many
slots remain fully accessible. It was most likely created BECAUSE of the
success of the original Compaq.
Colby? created an after-market case for 5150, that was smaller than
Compaq.
The 5150/5160/5155 had no real time clock. IBM didn't include that until
the 5170 (PC/AT). But there were MANY third party multi-function boards
the included addition of a real-time clock, so those need to be examined
for leakage, etc.
And, also, would this have a floppy controller on it that was capable
of reading and writing disks from systems like the TRS-80 with an SD
boot track?
Short answer: NO.
It could, with appropriate added software, read and write MANY DD/MFM
disks from other machines, including:
http://www.xenosoft.com/fmts.html
but NOT SD/MFM. And even boards that could, and the TRS80 model 3/4 had
difficulty with the "non-standard" DAMs (Data Address Marks) used on TRS80
model 1. There used to be an unconfirmed explanation saying that the
choice(s) of DAMs for the model 1 was due to a misprinted 765 spec sheet,
with 2 columns transposed.
The 5150/5160/[5155] FDC board used an NEC 765 (or equivalent) that was
hard wired for DD/MFM. In stock configuration, it did not permit SD/FM,
although it certainly could have been modified (non-trivially) for such.
Similarly, Flagstaff Engineering modified those FDC boards (quite a few
added wires), with added software, for 8" SSSD CP/M; but not 5/25" SD/FM.
Marty Goodman studied one, and copied those changes, to modify a few
imitations; but he no longer has any of them, nor his notes from the
project, and likely doesn't even remember doing it.
OB_Tangent: Sorrento Valley Associates made a floppy controller card for
the Apple2 that used an FDC chip, in order to be able to do 8" SSSD CP/M.
There were numerous third party FDC boards thet could do SD/FM, some of
which used the WD37C65 chip. David Dunfield provided a small program
that could test 5150/5160/[5155] and other PC FDC's for whether they could
handle SD/FM.
Inquiring minds want to know. :-)
The National Enquirer (who made popular the phrase: "Inquiring minds want
to know") had little or no coverage of microcomputers. THOSE inquiring
minds did not want to know.
--
Grumpy Ol' Fred [email protected]
http://www.xenosoft.com
