IBM 1 Series - Page 42

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Cycle steal request in or
request in bus of capturing
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Channel time-out
device (leading poll ID)
Cycle steal
request in or
request in bus
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of capturing
device __ x
(lagging poll ID)*
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Poll identifier
Poll
CT1
CT4
Burst return
T3
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iY
TS
Service sequences
CT3
Last transfer service gate return
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* = cycle steal request in or request in bus of capturing
device is lagging poll ID and did not cause poll ID.
Timings:
Ti < 100 ns (T1 may be negative)
T2 < T3 < 100 ns
T4 > 100 ns
TS > 0
CT1 > 180 ns
CT2 2 0
CT3 > 0
CT4 > 100 ns
CTS >0
Figure 2-12. Poll sequence with ‘burst return’ timing diagram
Key:
CT = channel times.
T = attachment controlled times.