elf-mon for 1802 and Membership Card


Last updated July 27 2011. Edited by Herb Johnson, (c) Herb Johnson, except for content developed by others. Contact Herb at www.retrotechnology.com, an email address is on that page..

This Web page is about elf-mon, a tiny 1802 monitor program provided through the Yahoo! group cosmacelf discussion group and written by Walid Maalouil using Lee Hart's 1802 Membership Card. Other Membership Card software is listed on the linked software Web page. For more info on the Membership card, the home page is linked here. - Herb Johnson

message posted in cosmacelf by Walid Maalouil July 2011:

"I've been playing with the ELF like a hyperactive gerbil lately, and ended up writing my own little monitor utility for the Membership Card ELF within 256 bytes. I know this has already been done ad nauseam, but it was an interesting exercise. The monitor has 4 functions, namely RUN, EDIT, LIST and DISPLAY REGISTERS (R1-RD). While the first three are the standard ones, the last one could be quite helpful in debugging (RE and RF are used by the monitor itself). Unfortunately, adding it made the program size a whopping 109 bytes, leaving only 147 bytes available for programs. On the other hand, anything much larger than that will likely need some kind of external PC link and a proper assembler. I already have a permanent sore on the tip of my index finger from repeatedly pressing that tiny I switch!" - Walid

With permission from Walid, his ELF-MON is available on the M/S card site. I've turned his HTML source/binary code into 1802 assembler, accepted by the A18 1802 cross assembler. The resulting files are:

elf-mon documentation
elf-mon source
elf-mon assembled listing
elf-mon Intel hex format

Let me know of any errors or corrections and I'll try to keep these updated.

- Herb Johnson, July 27 2011


Contact information:
Herb Johnson
New Jersey, USA
To email @ me, see
see my home Web page.

This page and edited content is copyright Herb Johnson (c) 2011. Contact Herb at www.retrotechnology.com, an email address is available on that page..