WRITE BYTE - Write the given data to the address given	(V40 SAD)

 Command:	$AF $01
 Data:		$ww $xx $yy $zz $qq

 Write the byte <$qq> to address <$wwxxyyzz>

 Command will be ACK'ed when received.
 Command ACK:	$00 $01
 Command DONE:	$1F $01

 BUGS
	This command does not exists in pre-V40 EXEC.
	This command can be emulated with the WRITE_ARRAY command with
	a length of 1.