The 5150, as released in August 1981, had SIX ROM sockets. It had one
8K ROM for the BIOS, four 8K ROMs totaling 32K for BASIC, and one empty
socket, which usually stayed empty. A company calling itself MBI sold
an accessory ROM for that socket thatr added some trivial features.
On Tue, 6 Jun 2023, Ali wrote:
I always wondered if anyone made use of the extra BIOS sockets. Do you
by any chance recall what functions were added?
I don't recall ever seeing any other than that MBI one. It's almost
certainly still sitting in the socket of my first 5150.
I never got around to using any of those functions.
I don't remember the details, but I think that it might have added some
print-screen functionality and some modes of the IBM printer (Epson MX80
with different ROM). Nothing that I ended up having need of.
If/when I dig it out, how much should I ask for it? (Berkeley California)
NO, Ed, I won't give it away AND pay shipping.
EARLY 5150, but with trivial modifications, such as additional holes in
brackets for 4 half-height drives, and probably has a different video
board and disk controller than the IBM ones that I originally bought with
it. At one time, I had a Plantronics 640x400 CGA-sorta-like video, and
I used 8 inch drives with a Vista disk controller, a Maynard, and maybe
one or two others (but only one disk controller at a time; I only did
multiple controllers with 5160 and 5170)
It had a D hole in the back panel, I might have punched an additional
D hole, . . .
I recall it having an unusual black power supply with a white switch (Did
IBM run short of inventory supply?), but I might have replaced that at
some point.
--
Grumpy Ol' Fred ci...@xenosoft.com
