B800 vs B1800, etc

From: Steve Wilson <stevew_at_ka6s.com>
Date: Sun Jul 25 06:37:04 2004

Well - to answer a series of questions ;-)

There were two separate operating systems available for the B1000
series. There was the standard MCP (that was similar in operational
characteristics between the B1000 and B2000 series at least) It didn't
have a common code base, but things worked in a similar manner from the
console (SPO in Burroughs speak.)

The other OS was "CMS" and ran on the B800/B1000 series. CMS was from
the Liege plant if I recall (Hans - is this right??) and I remember them
showing up in Santa Barbara where we were bringing up the B1965 at the
time. We had our MCP up with a couple of issues when the guys came in
from Liege to bring up CMS. It had one issue which was a new
instruction we'd added on the B1965 if I remember, other than that it
came right up! So from my understanding you could run the same
applications on the B1000 and B800 series.

Now - difference between B18XX and B19XX. Mostly cost reduction and
reimplementation in TTL. The B19XX may have been faster (a blistering
6Mhz ;-), likely had a larger memory sub-system, and I think they had
the same size instruction cache. The B19XX machines had a 4Kbyte
instruction cache.

The difference between B1955 & B1965. Well you've all seen how BIG the
B1955 was. The B1965 with soft console (which I LOVED working on...) is
about the size of a group of desk drawers on a standard desk! Maybe 2.5
feet tall, 20 inches wide, and 24 inches deep. (Real guess on that -but
it was a VERY small box.) It was every bit as capable as the B19XX
chassis. The Disc Controller was reimplemented as 5 cards using an
8086. There were two data com options, the single line and Multi-line
controller. The Multi-line controller was the only "DMA" device in the
system and was also a 8086 based design. The soft console was an 8080
implementation.

All this stuff had to be field testable/repairable so the soft console
designer (Dick Mogia) went to considerable effort in having two paths to
do everything. If the UART was dead, he had some 8255 parallel port
bits that he could bang out the serial code needed by the console to
show the problem through independent transistor drivers if the RS422
drivers were dead! It also controlled the the tape drive used by the
system to IPL - the UART did double duty here. With the addition of the
UART and a uP driving it, we found out just how bad the tape drives
REALLY were. Up until then it was done with a state machine! There
were really BAD parity error and tape errors that occured. The tape
didn't last long! We had the same kind of issues as the B80's floppy!
This was all revealed when we had something on there that could
categorize the types of errors we were seeing!

I had ALOT of fun working on the machine, and learned alot too!

Steve Wilson
Received on Sun Jul 25 2004 - 06:37:04 BST