From: drice@ponder.csci.unt.edu (Keith Rice)
Subject: Re: Taken delivery of an old PC... now what?
Organization: University of North Texas
Date: Thu, 3 Sep 1992 02:15:28 GMT

In <25393@castle.ed.ac.uk> asr@castle.ed.ac.uk (Angus "Fluffy" Rae) writes:

>Yesterday a friend, knowing that I collect computers from the early
>80's, dumped an old IBM PC on me. However, knowing nothing of PCs I
>don't know exactly what I've. After a quick shufty around under the case
>here's the info I have, and I wonder if someone out there can fill in
>the blanks. The badge on the back says IBM 5150, and it boots up into
>IBM Basic version C.01, which surprised me - I expected it to complain
>about not having a system disc.

Genuine IBM systems come up in "cassette" BASIC when a boot disk is not
inserted into the floppy drive and no bootable hard disk is present.

>                                The processor is an 8088, with a blank
>socket next to it (coprocessor)? On the board are 4 rows of Ics marked
>Bank 0 to Bank 3, which I take it is memory. Bank 0 is soldered, the
>other banks are empty sockets. (Question here is - can I fit more memory
>into the sockets, and what type?)

The blank socket is for an 8087 math coprocessor.  The three rows of empty
sockets are for memory expansion (just add the same type of chips that are
in Bank 0 and set the DIP switches on the motherboard to whatever amount
of memory you have (I don't have the info for that...sorry)).
>                                  Above this are two empty IC positions
>with solder dots, marked U100 and U101. There is also an empty socket
>marked U34. (Anyone know what should/can fit in them?)

Can't help you with that one.

>There are three boards in the slots - one is marked
>"Black&White/Parallel" and has a 9pin socket for the monitor and an
>unknown 25 pin socket, which I assume is a parallel printer port. The
>next card is marked "Addram Plus" and also has a 9pin and a 25pin
>socket. I assume that these are serial ports of some kind, but the card
>also seems to be a memory expansion of some kind. It has a large number
>of what seem to be RAM chips and a NiCad battery marked "DataSecurity".
>The third card is a disc controller.

The 25-pin socket on the video board is a parallel port.  The 9-pin
socket on the Addram board is serial and the 25-pin is another parallel
port, I think.  (You probably won't need to add memory to the motherboard
if you have the Addram.  You may need device driver software though.)
The battery is probably for a clock/calendar.

>The discs are 5.25 inch but I'm not sure how much they can hold, or
>whether they can access double sided or not. 

The disk drives take 360K DSDD diskettes.

>The questions I have in specific are - are early versions of DOS (that
>would fit on one 5.25 disc) available PD?

Nope.  All versions of DOS are copyrighted by Microsoft but I'm sure
someone has a (legitimate) copy that they may just give you with the
manuals.  If you were here in the US in Texas I would give you one of
my old version but, alas, you are not.

>                                          Can I replace the processor
>with something a little more speedy?

You can replace the 8088 with a V20 from NEC. It's slightly faster.

>                                     Or is there a coprocessor around
>that will fit in that blank socket? Does the AddRam board need some sort
>of boot software, as the Basic startup said I had 62k which seems a
>little low...? And why the heck am I bothering to do this?

(Coprocessor info and Addram info above.)  BASIC can only access a max
of 64K for its programs even if you have 640K of memory in your system.

>And why the heck am I bothering to do this?
>(I can answer the last one - because I'm mad)
>Thanks in advance...

--
D. Keith Rice -- University of North Texas -- drice@ponder.csci.unt.edu
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