On Mon, Mar 29, 2021 at 11:25 AM Alex ... <abortretryf...@gmail.com> wrote:
> Cool, so newbie mistakes and ignorance. As long as my computer's working > properly. :) > > What threw me off is in the book, (pg.25) it talks about returning usually > 0 and printing STACK EMPTY, which is definitely not how the machine behaved > when trying it. > > I don't expect everything to have bounds checking, but I'm using .S a lot > to inspect the stack, so having to reset the machine all the time and start > over kind of sucks. If I knew more about the system maybe I could rewrite > .S to know if it's looking at the stack or what's underneath? > Modifying .S to indicate a stack underflow error would be reasonable. It's a debugging tool, and not used by programs so it doesn't impact performance. Modifying stack operations with underflow guards would be prohibitively expensive performance-wise given Forth is a "stack machine" language and our 80C85 isn't a speed demon by any stretch of the imagination. A compromise would be to add underflow checking/correction to .S, and add a few cells of space beyond the stack to allow it to underflow a little without causing damage. -- John.
