IBM 1 Series Manual page 41

Cycle steal request in or |
request in bus of capturing y il
'Channel time-out
device (leading poll ID) |
aw
Cycle steal request in or 4
request in bus of capturing —— —-It
—_—_
device (lagging poll ID)*
|
|
'
Poll identifier
CT1
Poll
Poll return
Service gate
| ) >»
| AY
, CT4 a
/
|
l CTS
CT2 ~ va Ye TS
7
))
AN
CT3
Service gate return
* = cycle steal request in or request in bus of capturing
device is lagging poll ID and did not cause poll ID.
Timings:
Tl <100 ns (T1 may be negative)
T2 <T3 < 100 ns
T4 < 100 ns
T5 >0
CT1 > 180 ns
CT2 >0
CT3 >0
CT4 > 100ns + T4
CTS > 0
Figure 2-11. Poll sequence with 'poll return' timing diagram
Key:
CT = channel times.
T = attachment-controlled times.