[Coco] Basic09 question

[Robert Gault]

Bob Devries wrote:
> Does anyone know if you can trap the BREAK (ESC) key in Basic09?
> 
> My experiments so far just seem to show that Basic09 just quietly quits 
> the programme when you press BREAK.
> 
> Can anyone give me some pointers?

Good question fir which I don't have a good answer.

Running NitrOS-9, Basic09 will not trap either BREAK or shift-BREAK. In 
fast the original version of Basic09 won't even respond to the BREAK 
key. Basic09 had to be patched for NitrOS-9 use. It is possible that the 
patch does not vector the BREAK key correctly but the Basic09 manual 
suggests otherwise.

"ON ERROR GOTO is effective only with non-fatal, run-time errors." In my 
mind, errors 2 & 3 are fatal run time errors so would not have been 
trapped by Basic09 under either OS-9 or NitrOS-9. That's not to say 
trapping is impossible.

on error goto 1
loop
error 2
endloop
1 print err

The above will exit with 2 meaning that either there is no 
discrimination in "on error goto" or "error 2" does not really create an 
"error". I think that this may be a bug/feature in Basic09 that would 
need extensive study of the source code to fix.