Control Data Cyber 170 State Hardware Reference Manual page 37

instruction Section
CYBER 170 Exchange Sequence
The CYBER 170 exchange sequence i s t h e method used t o swap jobs i n and o u t o f
e x e c u t i o n . When a CYBER 170 exchange jump i n s t r u c t i o n o c c u r s , t h e CYBER 1 7 0
exchange sequence w r i t e s t h e c o n t e n t s of t h e c u r r e n t j o b ' s C P r e g i s t e r s
( d e s c r i b e d l a t e r in t h i s c h a p t e r ) i n t o an a r e a of c e n t r a l memory c a l l e d a
CYBER
170 exchange package. A CYBER 170 exchange package i s a s s o c i a t e d w i t h
each job.
It c o n t a i n s s u f f i c i e n t i n f o r m a t i o n t o r e s t a r t a job i f t h e job i s
i n t e r r u p t e d d u r i n g e x e c u t i o n and swapped o u t by a C Y B m 170 exchange jump.
To
complete t h e sequence, CP r e g i s t e r s f o r a n o t h e r job a r e r e a d from i t s CYBER
170 exchange package, and t h a t job b e g i n s o r resumes e x e c u t i o n . For f u r t h e r
i n f o r m a t i o n , r e f e r t o CYBER 170 Exchange Jump i n c h a p t e r 5 .
Block Copy Sequence
The block copy sequence c o n t r o l s t h e t r a n s f e r of d a t a between
CM
and
UEM. The
a d d i t i o n of K t o t h e c o n t e n t s of Bj determines t h e number o f words t o be
t r a n s f e r r e d . The s t a r t i n g a d d r e s s f o r CM i s formed by adding e i t h e r t h e A 0
r e g i s t e r o r c e r t a i n b i t s of t h e XO r e g i s t e r t o t h e RAC r e f e r e n c e a d d r e s s . The
s t a r t i n g a d d r e s s f o r UEM i s formed by adding c e r t a i n b i t s of t h e XO r e g i s t e r
t o t h e RAE r e f e r e n c e a d d r e s s .
The
block copy i n s t r u c t i o n s a r e :
O U
Block copy B j
+
K words from UEM t o CM BE B j
+
K
012 Block copy Bj
+
K words from CM t o UEM
W E B j
+
K
Direct Read1 Write Sequence
I n s t r u c t i o n s 014 and 015 perform single-word, d i r e c t r e a d and w r i t e o p e r a t i o n s
f o r UEM, and i n s t r u c t i o n s 660 and 670 perform single-word, d i r e c t r e a d and
w r i t e o p e r a t i o n s f o r c e n t r a l memory.
014 Read one word from UEM a t (Xk
+
RAE) i n t o Xj R X j Xk
015
Write one word from X j t o
U M
a t (Xk
+
RAE)
WXj Xk
660 Read c e n t r a l memory a t (Xk) t o X j CRXj Xk
670
Write X j i n t o c e n t r a l memory a t ( X k )
CWXj Xk