IBM 5120 (was Re: My First S-100 System)

From: Eric Smith <eric_at_brouhaha.com>
Date: Sat Oct 12 21:36:00 2002

"Otter" <SecretaryBird_at_SoftHome.net> wrote:
> I was finally able to get a good look at the back. It is an IBM
> 5120. There's four ports on the back; 2 DB-25 female, 1 female port
> that looks like an AUI port, and a BNC connector. I just did a
> lengthy search via Google, and so far have been able to find any
> actual specs on this beast. But I'm guessing that one of the DB-25
> ports is RS-232, and the other is probably a parallel port of some
> sort.

No, the 5120 doesn't have parallel ports. They would both be serial,
although it's quite possible that one is synchronous.

> So, the 5120, if my guesses are correct about the ports, will serve
> fine as a control console for the Cromemco System Two.

The 5120 is an interesting machine, and I very much want one; it's a
5110 repackaged into the all-in-one unit, and depending on the model has
BASIC, APL, or both in ROM. The 5110/5120 is a somewhat improved
version of the 5100, with better language interpreters and more I/O
capabilities.

But it would make an absolutely *terrible* terminal. It only has 16*64
video, and unless you got the terminal software with it, you'll have to
write your own. In BASIC or APL, depending on which model you have.
I seriously doubt that it can keep up at 9600 bps or faster; as a
terminal they were normally only used for dialup at 300 bps or slower.

It's full of proprietary IBM chips, including the processor, so it's
all but impossible to run anything but the standard BASIC and APL
interpreters on it. In principle it is possible to load machine code
from disk (there's some on the diagnostics disk), but it's not documented
so very little assembly code was every written for it by anyone outside
IBM.
Received on Sat Oct 12 2002 - 21:36:00 BST