OSBYTE &84

OSBYTE &84 (132) - Read top of user memory

   On exit X and Y point to the first byte after the top of user memory,
   used to initialise BASIC's 'HIMEM'. If b7 of A is clear, then A:Y:X
   holds the 23-bit address of the top of user memory, as when running
   6502Turbo code on a CoProcessor, which returns A=&04, XY=&0000.

See Also

• http://mdfs.net/Docs/Comp/BBC/Osbyte80

Jgharston 21:59, 26 May 2009 (UTC)