IBM Series 1 User Manual page 35

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W
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o
o
w
w
Poll group resources
Interrupt ~
"' request
G
oJ
Poll for
" " -
interrupt
I
Poll return G
OR
t - - -
(A)
; - - -
1-
Cycle steal
~
" request
G
Poll return G
Poll for
(A)
L . . . . - -
cycle steal
I
(B)
Burst return
OR
~
-
I
egend:
Transaction block
G
SA
--
State of
(A)
channel
---
I
G
--
(B)
---
L - - -
G
- Gate (enables sequences)
I - Inhibit (prevents sequences from starting)
SA - Sequence active (shows that particular sequence is in progress)
A, B - Signals indicating end of sequence that conditions the next
sequence (only one may be active)
" Operate I/O instruction
I
lote:
) Logic blocks are zero delay
) A poll sequence and service sequence
may be active simultaneously when allowed
~
'" #
Service group resources
Wait
SA
for
service
G
Interrupt
acceptance
Wait
SA
I
for
I - - - -
service
G
-
Cycle steal
single sequence
~
I
OR
Wait
SA
G
for
service
Cycle steal
burst sequence
~
G
DPC
- sequence
~
I
OR
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SA
OR
~
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SA
SA
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