IBM 1 Series - Page 29

81-2
teO00-VEVD
Poll group resources
Service group resources
OR
OR
Processor interrupt
poll request G SA
Poll for Wai
I interrupt Poll return at SA
| for
service
G
Interrupt SA
Cycle-steal request G (A) SA qe acceptance
Poll for Poll return nn SA
cycle-steal Or
I (B) Burst return service
G
Legend: G]| Cycle-steal SA
Transaction block 6 [| single sequence
G SA
State of Burst return drop
channel ‘A)
I anne
(B) Wait SA G
| for ——@
G —Gate (enables sequences) service Cycle steal SA
I —Inhibit (prevents sequences from starting) I burst sequences
SA — Sequence active (shows that particular sequence is in progress) qe
A,B — Signals indicating end of sequence that conditions the next
sequence (only one may be active)
Processor DPC request G
DPC SA
I sequence
Notes:
1. Logic blocks are zero-delay.
2. A poll sequence and service sequence may be active
simultaneously, when allowed.
Figure 2-7.
Channel sequence interdependencies