Xerox 550 Reference Manual page 183

Term
WK
x
Meaning
Write key - bit positions 32, 33, 34,
and 35 of PSWs; they are evaluated by
the memory write-protect feature to de-
termine accessibility of real memory by
current program.
Index register address value - 3-bit con-
tents of bit positions 12-14 (X field) of
instruction word. In instruction word,
if X = 0, no indexing is performed;
176 Appendix B
Term
X
(cont .)
X'n'
Meaning
if X
f.
0, indexing is performed (after indirect
addressing if indirect addressing is called for)
with general register X in current register block.
Hexadecimal qualifier - hexadecimal value
(n) is unsigned string of
tiexad~cimal
digits
(O through 9 and A through F) surrounded by
single quotation marks and preceded by the
qualifier "X" (for example, 7B0 16 is written
X'7BO'.