I'm reasonably sure the old polling stuff still works, at least in 
basics since the RISC OS vm has been using it until very recently.

Exceptions shouldn't cause any problems since the vm doesn't raise any 
unless the image says to. The exception stuff in the vm only does the 
scanning up the stack on returns & explicit prim call so the worst case 
ought to be nothing worse than returns being a little slower than 
without the code.


tim