1 DFX
	In response to "DFX>" prompt, type
	L	to list referenced block
	W	to write the currently referenced block back onto disk
	N	to read the next block
	R	to reread the current block (overwriting current buffer)
	B	to read the previous block
	F	for full-word addresses (defaults to byte addresses)
	H	for half-word (byte) addresses in block
	T	to type out the block as ascii text
	S	to set/clear flag for spooling output file to LP0:
	K	to calculate checksum of first 255. words of block
	E	to exit to the monitor
	M/nnnnn	change buffer word to the octal value 000000
	M,LLL	change buffer word to rad50 vaLue of "LLL"
	M;AA	change buffer word to ascii value of "AA"
	M:	display buffer word in octal, rad50 and ascii
	D,N	to change default block number for read and write to N 
	A,N	to read and list block N (N absent implies next block)
	C,N	to read and list all blocks up to and including block N.
	P,N	changes the high-order block number from the disk.
 
	note that lun 4 must be re-assigned to the disk to enable write-back