NOTES ON THE CROMEMCO 3K CONTROL BASIC AND MONITOR ROMS

These files represent the two proms furnished as part #MCB-216 from
Cromemco. File MCB216R0.HEX is EPROM 0, and should be burned into a
2716 and is then plugged into a Cromemco Single Card Computer (SCC)
in socket 0. This EPROM has code that resides at address 0000-07FFh.
File MCB216R1.HEX is EPROM 1, and should be burned into a 2716 and
is then plugged into the SCC is socket 1. This EPROM has code that
resides at address 0800-0FFFh.

Sockets #2 and #3 on the SCC were available to hold Basic programs
that were AUTOSAVE'd (see the Cromemco 3K Control Basic manual). Any
AUTOSAVE'd program runs immediately at startup, setting a default
terminal baud rate of 9600. If no AUTOSAVE'd program is present, the
software assumes interactive mode and waits for the user to press RETURN
several times on an RS232 terminal attached to J4, and after 2-6 RETURNs
can detect and match baud rates of 19,200, 9600, 4800, 2400, 1200, 300,
150, or 110. Once matched, the software prompts with "OK" and a ">"
prompt, ready for BASIC program input.

This product was designed to run with the SCC and (optionally) some
additional RAM. The SCC is equipped with 1K of RAM at address 2000-23FFh,
and 3K Basic will run quite nicely with this limited memory, although this
leaves very little RAM to hold the BASIC programs (about 512 bytes) you
input.

These EPROMs also include Cromemco's Z80 monitor in low memory (see
Cromemco Z80 Monitor manual for instructions and full source code). You
can easily move between the monitor and Basic. In BASIC, enter "QUIT" to
jump into the monitor and from the monitor, enter "B" to jump back to
BASIC. Note that the monitor included in the ROMS does not support the
UART command documented in the Z80 monitor manual and the display register
command appears to provide different results from what is documented,
- see the MCB216 product notes in the 3K BASIC manual for full details.

I originally purchased the SCC and MCB216 EPROMs in conjunction with
a project I did at Planning Research Corporation around 1982. I copied
the product PROMs at that time in order to have a backup, since our
project called for completely custom code for the SCC. In later years
after leaving PRC and taking up the hobby of restoring old S100 systems,
I patched the copies to allow the product to run on other boards and
memory configurations. In the process I lost the originals. The code
in these two HEX files represents many hours of effort to restore the
code to its exact original configuration, using the Z80 monitor listing,
3K BASIC documentation, and my original notes. I believe these files to
now be exact duplicates of the originals. Cromemco built some of the
finest hardware and software products for S100. A Cromemco board always
had a clean, manufactured, and well-designed appearance and you could
depend on their outstanding product documentation and high standards of
quality.

Have fun.
Sincerely,
Craig Landrum, CTO
Mindwrap, Inc.
PO Box 430
Flint Hill, VA 22627
(w) 540-675-3015 x 229
(h) 540-987-9549
craigl@mindwrap.com