We currently take advantage of the BASIC ZP area, but commodore family
targets can only load programs from a BASIC environment. This makes it
intrinsically unsafe to exit by return, since it always returns to a
possibly-clobbered environment.
Instead, exiting by looping still allows a screen's worth of output to
be viewed, without possibly returning to a broken BASIC interpreter.
This is arguably a bugfix, but it's also a very significant change in
behavior, so I'm considering it a breaking change.
We should also have an optional library that saves and restores BASIC ZP
on entry-exit and exits via returning, but that shouldn't block this
change.
mysterymath
commented
1 week ago
We currently take advantage of the BASIC ZP area, but commodore family targets can only load programs from a BASIC environment. This makes it intrinsically unsafe to exit by return, since it always returns to a possibly-clobbered environment.
Instead, exiting by looping still allows a screen's worth of output to be viewed, without possibly returning to a broken BASIC interpreter. This is arguably a bugfix, but it's also a very significant change in behavior, so I'm considering it a breaking change.
We should also have an optional library that saves and restores BASIC ZP on entry-exit and exits via returning, but that shouldn't block this change.