Todo
				     ====

*	Change printing of characters. We should use our own print routine
	(rather than OSWRCH) that prints spaces (or maybe changes colour using
	other VDU codes) when not in MODE 7.

*	Should we change behaviour of MEM so that it only writes the modified
	byte to memory upon movement or quitting (hence removing problems when
	writing to memory mapped IO)? Comments please?

*	Scrolling up in MDIS uses bizarre behaviour. Currently it scrolls up
	by the same number of numbers needed to scroll down from that
	position. Ideally we'd like to either always scroll up by one byte, or
	by as few needed to produce a valid opcode (max 3).

*	Decide correct behaviour for '+' in strings (see 'Current syntax
	problems' below).

*	Finish writing other numerous commands (obvious really)

*	Possible speed improvements on MEM and MCOPY, MFILL, MSWAP, etc to do
	with block IO from other banks.

*	Write decent documentation

*	Implement private rom-table for making sure that roms stay off after a
	break if they have been *ROFF'ed. Also for use by commands which use
	sideways ram for buffers, ie *FBACKUP and *PBUFF.

*	Implement oswords and osbytes for various useful-subroutines.