This macro tells the IDE how much memory to try to give the transfer program.

The IDE gives up as much memory as possible, up to either the amount specified or the maximum available, whichever is smaller. You'll get an error if no memory is specified.

If you use $MEM(), you can specify (on a program-by-program basis) how much memory the IDE should give to the transfer programs.

The less memory you devote to a transfer program, the quicker the transfer to and from the program occurs.

In cases where the IDE can't give up as much memory as you request, it gives up as much as it can.

Certain states in the IDE require more memory than others. For example, while debugging a program, the IDE will tie up more resources than when not debugging.

In cases where you want the IDE to give up all of its memory, give $MEM() a large number, like 640K.