Quote:
This may sound a little like teaching granny to suck eggs but...
In theory it should work


It could have been that my assembler routines were buggy !! .. Well definitely... I had a loop which wasn't exiting cleanly - and it had self modifying section in it. Yes I was overwriting code via the bugs so the code wasn't returning neatly.
EDIT: The bugs resultied in the end of the assembled code being overwritten with BRKs, as per one of the reasons you gave above.
Debugged now and the BASIC prog is running as expected.
Thanks for taking a look sweh [he said sheepishly]