Control Data Cyber 170 State Hardware Reference Manual page 206

PP
Programming
Direct 6-Bit Address
PP i n s t r u c t i o n s i n t h i s category a r e d i r e c t - a d d r e s s i n s t r u c t i o n s . They have
t h e format OPCODEd.
The d f i e l d i s used
as a 6-bit d i r e c t a d d r e s s , a c c e s s i n g
PP memory l o c a t i o n s 0 t o 778.
Direct 12-Bit Address
PP i n s t r u c t i o n s i n t h i s category a r e indexed d i r e c t - a d d r e s s i n s t r u c t i o n s with
zero index. They have t h e format OPCODEdm where d e q u a l s 0.
The m f i e l d is
used a s a 12-bit d i r e c t address t h a t a c c e s s e s PP memory l o c a t i o n s 0 through
77778.
Indexed 12-Bit Address
PP i n s t r u c t i o n s I n t h i s category a r e indexed d i r e c t - a d d r e s s i n s t r u c t i o n s . They
have t h e format OPCODEdm where d e q u a l s 0.
The m f i e l d i s used a s a 12-bit
d i r e c t a d d r e s s (base a d d r e s s ) . The d f i e l d s p e c i f i e s a PP memory l o c a t i o n from
1
t o 77
,
the c o n t e n t s of which i s a 12-bit one's complement number index.
The indgxed d i r e c t a d d r e s s
is
formed by adding t h e index t o t h e base a d d r e s s a s
signed one's complement numbers.
Overflow
i s
ignored.
When m p l u s ( d ) e q u a l s
7777,
t h e r e s u l t i s s e t t o 0000, except as follows: adding
7777
p l u s
7777
e q u a l s 7777.
I n
g e n e r a l , adding 0000 o r
7777
l e a v e s t h e o t h e r number
unchanged, except when t h e o t h e r number i s a l s o 0000 o r
7777.
Indirect 6-Bit Address
PP i n s t r u c t i o n s i n t h i s category a r e i n d i r e c t - a d d r e s s i n s t r u c t i o n s . They have
t h e format OPCODEd. The 6-bit d f i e l d
i s
used t o read a 12-bit number from PP
l o c a t i o n s 0 through 77
.
This number i s used a s a 12-bit a d d r e s s t o a c c e s s
PP memory l o c a t i o n s 0 fhrough 77778.