IBM Series 1 User Manual page 47

activation of poll return or burst return at the
processor channel input. When the device detects the
leading edge of poll, the device must take action to
either capture or propagate the poll. The capture is
based upon the poll ID and the state and level of
request as determined on the activation of poll ID.
If
!h~
£011
12
E£opagated (Figure 2-13)
4. The device activates the poll propagate line to the
next device attachment on the channel. The poll
propagate output is the image of poll, with
a
delay,
T2, of 200 nanoseconds
maximum.
Once a poll is
propagated from the device, the device may take no
further action until the activation of the next poll.
However, if the device detects a Halt or
MeHK,
system
reset, or power on reset, the poll propagate tag is
deactivated regardless of the state of the poll at the
device input.
5.
6.
11
the ,Eol,! is captured (Figures 2- 11 and 2-12)
The device activates poll return or burst return as
appropriate, and deactivates the appropriate request
line. The request line must be deactivated prior to
the activation of pallor burst return. The poll or
burst return must be activated at a time* T3, of 100
nanoseconds
maximum
from the activation of poll as seen
at the device interface.
For interrupt service sequences, the activation of poll
return causes the normal service gate sequence to begin
without any intervening DPC sequence. This is
necessary to preclude a device reset from occurring
between the poll and service sequences and is necessary
for proper implementation of device reset. The service
gate may occur immediately or
may
be delayed
considerably
if
another device is finishing a service
sequence.
For cycle steal operations, service gate may occur
immediately or this tag may be delayed considerably if
another device is finishing a service or DPe sequence.
7. Poll and poll ID are deactivated. The time that poll
ID remains at the quiescent value, CT4, is 100
nanoseconds minimum as seen at the device interface.
However, poll ID cannot be reactivated at the processor
channel output prior to the deactivation of poll or
burst return at the processor channel input.
8.
2-32
InterruEt Q!:
sing!~
transfer
QY5:!!! ~al
(fg.!l
Ret urn)
When poll becomes
deactivated within
seen at the device
present another
inactive, poll return must be
a tilDe, T4, of 100 nanoseconds as
interface. The device must not
request in until service gate return
GA34-0033