20 May
2025
20 May
'25
3:51 p.m.
On Tue, May 20, 2025 at 2:38 PM Bill Gunshannon via cctalk
<cctalk(a)classiccmp.org> 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.
I restored one last year. Mine is still 100% orginal IBM too.
It's a normal PC/XT motherboard with CGA and floppy controller boards
at least. Technical references for everything apart from the power
supply are on bitsavers. Theres another site with some detailed
information on the power supply and I think I found the sources for
the keyboard microcontroller as a Github project.
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?
No, it's a XT, so no internal real time clock or CMOS configuration
RAM as standard.
What you do need to replace before they do their antisocial acts and
emit clouds of magic smoke are the metalised paper capacitors in the
power supply. This is painful to do, you have to dismantle the power
supply which involves Bristol Spline and tamperproof Torx screws, then
drill out rivets holding the little filter PCB in place. Rivets that
are hard to get a drill to.
The only other part I had to replace in mine was a tantalum bead
capactor on the motherboard.
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?
Alas not. The oriignal IBM controller is strictly double density (MFM) only.
-tony