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response to status-in during an
initial selection sequence with
the status on bus-in including
attention, control-unit end, unit
check, unit exception, busy,
status modifier (without
channel end and device end),
or device end (without channel
end).
3. When a short, control-unit-
busy sequence is signaled.
4. When command retry is
signaled.
5. When the channel issues a
test-I/O command rather than
the command in the current
CCW.
101 The command has been accepted,
but data transfer is unpredictable.
This code applies from the time a
device comes on the interface until
12-62
IBM 4300 Processors Principles of Operation
the time it is determined that a new
sequence code applies. The code
may thus be used when a channel
goes into the polling or idle state
and it is impossible to determine
that code 010 or 011 applies. The
code may also be used at other
times when a channel cannot
distinguish between code 010 or
OIl.
110 Reserved.
111 Reserved.
Reserved (Location 185): Zero is stored at
location 185 whenever an I/O address is stored at
locations 186-187.
I/O Address (Locations 186-187): A two-byte
field is provided for storing the I/O address on
each I/O interruption in the
Be
mode.
(
\,
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