BNAMEb
   Assem - Assemble source code from files

BSYNOPSISb
   B*Assemb filename

BDESCRIPTIONb
   When writing very long machine code programs (eg roms, etc.) using the
   in-built Basic assembler, there comes a point where you cannot fit both
   the source code and the generated object code into the machine memory
   at the same time.  To solve this, you could buy a 6502 machine code
   development package that allows you to write machine code and assemble
   it from disk.  However, I always prefer to use the facilities provided
   on the machine already, and you can easily persuade the Basic assembler
   to assemble from a file instead of from memory.  This is what the
   *ASSEM command does.

Each source file should be of the following layout:

First source file:
REM > Part0
Set any variables
DIM mcode% size_of_space
Block%=object_code_start
O%=mcode%:P%=Block%
[
Assembly code
]
> Part1

Middle source files:
REM > Part1
[
Assembly code
]
> Part2

Final source file:
REM > Part2
[
Assembly code
]
Save$="*Save name "+STR$~mcode%+" "+STR$~O%

NB: There is also a way to assemble from file to file.