Date   : Thu, 18 Oct 1990 21:22:19 GMT
From   : agate!shelby!msi.umn.edu!cs.umn.edu!ux.acs!hughes@ucbvax.Berkeley.EDU (Steve Hughes)
Subject: Is this a Xerox 820 micro? If so, now what?

Okay, here's a hardware ID challenge:
In the hopes of saving a few buck$ and putting off
buying a computer of my own (I program at work on a IIci,
getting a machine I can actually afford would be just to pitiful),
I have bought a cheap terminal from a local surplus shop.
I wanted to get something to dial up the mainframe with, using my
old 1200 baud modem that has been idle since I sold my IIe.
They had lotz of Adm3as and a few CDC and a couple of Hazeltine
1420's, (none of which worked) all for $39. After screwing around with 
what they had for a couple of hours, I settled for an
unidentifiable Xerox terminal that had a solid looking screen and
a very nice detatched keyboard.  I was able to get it to work well 
with an old 300 baud modem in the shop, so I figured I'd give this one a shot.

Now here is the deal: No documentation, and despite my best
efforts, I cannot make it work at higher than 300 baud! Not with my
(admittedly ancient, Novation Auto-Cat 212) modem or with a direct
connect to an IBX box (on campus) capable of up to 9600 baud.  This is
nuts; it was built in 1984, it simply MUST be capable of faster
operation, and I am hoping that someone reading this knows
about this machine and can help me out.

Here is as much as I know about it:
ABSOLUTELY NO DIP SWITCHES.
Product Code (from bottom of monitor unit): UO5. 
Description: Monitor is green filter over a white phosphorous crt,
detatched keyboard, keyboard has numeric keypad on the right side,
"Xerox" nameplate in upper left corner of keyboard unit. "Help"
key in upper left corner of keyboard (where you might expect to find "esc").

There is a COMM port, Printer Port (RS-232) and for God's sake,
a DISK DRIVES port and a reset button on the back of the unit.  
I open the case to check things out: I find a Z-80 MPU.
The machine starts up with a beep and displays the following message:

Xerox v 4.04 C 1982 Xerox Corp.

     L - Load System
     H - Host Terminal
     T - Typewriter

*

The "*" is, apparently, a monitor program prompt. Pressing the "Help" key
from the * prompt yields this result:

Baud     <rate> [B/A]
Dump     [start] [end]
Goto     <addr>
Modify   <addr>
Protocol <xon> [msk val]

Looks like I could type "baud 1200" or something like that, right?
Thats what I thought, no dice. There appear to be other monitor commands,
for example, "w" yields "C1981BALCORESCOMPUTER" and some commands like
"e" or "a" seem to produce some result, sometimes an apparent
hang, sometimes something like:
m 
0000   00  <-stops here and waits for me to type a hex digit, then
             continues

After I've done something online (at @%$# 300 baud) I can reset the
machine (via the reset button on the back), get the * prompt back, and use
the "d" (dump) command to generate a nice hex and ASCII scroll through
RAM, and sure enough, my whole session is sitting there! 

Seems like I should be able to replay my session, scroll up and 
down, etc., but God (and Xerox) only knows how. Despite the Copyright
dates, the machine has stamped on the bottom of the monitor unit
"Manufactured Sept 1984." Opening the case shows a Z-80 board with
all kinds of jumpers, pins and ROM chips with "v 4.04" printed on their
labels. Also one card plugged into an edge connector.

Other fun:
The command "Parity even" seems to be digested by the monitor program,
other attempts at discovering commands yield a beep and "what?" so
I can tell what sort of input at least gets accepted. I can't seem
to make the "baud" command choke by typing, say, "baud huppho" or 
something. No luck with stuff like "set" or "VT100" (it was worth a
try at least!).

Typewriter mode lets me type on the screen, and I assume, would pass
characters through to a printer if attatched. L for Load system
results in a hang, I assume it is trying to boot from floppy drives
which, of course, I have not. After entering typewriter mode or
host terminal mode I get the message "ctl-esc to exit", which takes
me back to the "*" prompt.

So the bottom line is, What do I have here besides a fun little Z-80
micro and part time extremely dumb, 300 baud terminal?
Screen sure is solid, keyboard very nice, it's pleasant enough to _use_
but working at 300 baud is driving me nuts!

Does anybody know anything about my mysterious Xerox UO5?

If you do, please email me at:

hughes@ux.acs.umn.edu

Since this is a Z-80 machine, it must have run CP/M, and I have
recently heard that it may in fact be a Xerox 820 microcomputer.
If this is so, I would be very interested in buying a copy
of the users manual from someone. I don't think I would be
interested in disk drives, etc, but I would be intersted in
discovering if the ROM host terminal mode supports some kind
of terminal emulation, or if it will allow me to set parity, stop
bits, etc..

I've got to believe that someone reading comp.os.cpm has used this
machine!

Any help at all would by much appreciated.  Thanks!

-Steve