INTERCPM.ASM   COPY FILES BETWEEN 5" AND 8" CP/M
    WRITTEN BY G. YOUNG, PO BOX 3218, NORTH HOLLYWOOD, CA 91609

    THE SITUATION AROSE THAT I WANTED TO COPY CP/M FILES FROM MY NORMAL 8"
SYSTEM TO MY CP/M SYSTEM ON 5" NORTH STAR DRIVES.  THE BIOS FOR THE 5" WAS
NOT AVAILABLE, SO I HAD TO "TRICK" CP/M TO DO THE COPY.  MY NORMAL CP/M
WAS LOCATED AT THE TOP OF 56K AND THE 5" CP/M WAS LOCATED AT THE TOP OF
32K THEREBY ALLOWING BOTH COPIES OF CP/M TO BE IN MEMORY AT ONE TIME.  
INTERCPM WAS A PROGRAM THAT WAS LOADED BY THE 8" SYSTEM AT 100H BUT THE
ONLY CODE AT 100H WAS A JUMP TO 500H WHERE THE REAL CODE FOR A SIMPLE FILE
COPY PROGRAM WAS LOADED. AT 500H, THE PROGRAM WOULD BOOT THE 32K SYSTEM
SO NOW THERE ARE 2 COPIES OF CP/M IN MEMORY.  IN THE 32K SYSTEM I WOULD
RUN A PROGRAM CALLED "JP 0500" (HANGOVER FROM THE NORTH STAR DAYS).  THIS
PROGRAM WOULD ALSO LOAD AT 100H, BUT SINCE MOST OF INTERCPM WAS AT 500H,
INTERCPM WAS NOT DESTROYED.  "JP" WOULD JMP TO 500H AND REENTER INTERCPM.
NOW THERE ARE 2 COPIES OF CPM IN MEMORY, INTERCPM KNOWS ABOUT BOTH OF THEM
AND HAS SAVED THE CALL TO BIOS AT 5H OF THE 56K SYSTEM AT ANOTHER LOCATION
SO THAT THE 32K SYSTEM COULD PUT ITS CALL TO BIOS AT 5H.  INTERCPM THEN
DOES SUCCESSIVE CALLS TO BOTH CPM'S TO COPY THE FILES TO/FROM THE 5" AND
8".  RECORDS ARE ONLY BUFFERED 128 BYTES AT A TIME SINCE MUCH OF MEMORY
IS TAKEN UP BY THE OTHER CPM SO IT IS NOT REAL EFFICIENT, BUT IT WILL
DO THE COPY CORRECTLY IN THE FEW INSTANCES THAT I NEEDED IT.