28 Aug
2025
28 Aug
'25
10:07 a.m.
On Thu, Aug 28, 2025 at 5:51 PM Bill Gunshannon via cctalk
<cctalk(a)classiccmp.org> wrote:
I finally got the missing keyboard and now it is time to try
and revive it.
I restored one some months back. Mine is 100% IBM boards and options....
The portablePC has a normal XT motherboard in it. The standard video
board is the CGA one, with the composite output (on the 4 pin
connector originally designed for an RF modulator) feeding the
internal amber moniitor. This is actually a Zenith unit.
Note that if you want to remove or open up the monitor and PSU you
need Bristol Spline tools. And tamperprrof Torx for the PSU cover. I
had to take the latter apart, the mains input filter capaciitors were
being antisocial and breaking down. I replaced them before they filled
the worshop with magic smoke
A couple quick questions.
It has a board in it called IBM PC INTERFACE with the numbers
170-18-165 and CIL18-16 printed on it. It has a 50 pin connector
on the bracket end. If I take it out the machine dies almost
immediately doing the POST. Tried Google with no luck. Anybody
remember what it is?
This doesn't sound like any IBM board. Is there a maker's name on it?
And how does the POST die? What error code, etc.
Are there any large chips on the board, or is it all small TTL devices?
Next problem. 1701 error. Light on MFM drive flashes 3 slow
and 4 fast continuously. Being as this machine was known to
work when it was last shut down any suggestions? Could it be
a stiction problem and the disk just isn't spinning up? (Can't
tell by listening as the fan is pretty loud. Not bad just louder
than any good disk I have ever heard.)
I am pretty sure that the only official way to add a hard disk was to
put it in a 5161 expansion cabinet (!) So this must be a 3rd-party
devce, What is the make and model of the hard drive itself? Do you
have a way of powering it up outside the machine? Just power it, with
no ribbon cables connected
And then one other not related to a problem. Being an original
PC owned by users and not geeks is it likely that the floppy
controller is one that can handle other formats (like TRS-80)
and maybe even 8"?
The original IBM floppy controller is a 3/4 length card. Theres an
edge connector at the front for the ribbon cable to the internal
drives and a DC37 socket on th bracket for the external drives. Mostly
small ICs with one 40 pin device (NEC 765 or Intel 8272, they're
essentially the same).
This board is strictly double density, standard data rate only. It
won't do 8" data rates. It won't do single density.
And just to wrap it up. What are the chances of
finding an
external drive or even a cable that could be made to connect
to an external drive?
Very easy to make the cable using an IDC DC37 plug, 34 way ribbon
cable and the sockets/edge connectors to fit your drives. I am sure
there are instructions on the web.
-tony