I seem to be plagued with problems.
Tonight I started actually writing and using some test code I had come up with, to sort of model the flow of the program and to see if my plans would actually work. But I've hit a sort of rough point. The MERGE command that I mentioned yesterday was not described in any detail in the manual, and upon using it, I found that what it does is actually appends the source file that you specify to the end of the main program while it is running, and then starts over at the beginning of the program. This does not suit my needs at all. I've found a couple of other methods - CHAIN, RUN, and $INCLUDE - but all have certain drawbacks.
RUN is almost completely out as soon as it starts off; variables aren't passed, the screen is cleared; overall it just doesn't work the way I need it to. CHAIN at first seemed a good candidate, but if the MERGE option is checked (which in my case it would need to be) it seems to merge the external source file correctly, but then it restarts execution of the program from the beginning, which causes all sorts of errors when I try to declare variables that have already been declared. $INCLUDE is something I've used before in QuickBASIC for DOS. It is a compiler directive that instructs the compiler to halt compiling on the current file, then to compile the external source file, and then to pick back up where it left off. The drawback is that since it is a compiler directive, the interpreter ignores it, and so I can't run the code in the QuickBASIC environment. I've been doing this on DOS for some time, but as I've said before, QuickBASIC was (compared to its DOS cousins) a substandard product...
For about 10 minutes or so, I actually considered switching to FutureBASIC or some other compiler that I could get to work with System 6, but I was too lazy to transfer 1.5MB worth of files via floppy disk :) So I decided to stick it out with QuickBASIC. In the end, I've chosen to work with $INCLUDE, even if it means I have to do a complete compile any time I want to test something. But oh well. That's how they did it in the old days...
