IBM Series 1 - Page 30

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(~
o
Pol,! Identifier. This is a 5-bit outbound bus used by the
channel to indicate the nature of the poll presently being
propagated to the I/O devices. The poll identifier is
always recognizable by I/O devices that are capable of cycle
stealing and/or presenting interrupts to the processor. The
channel places a value on the poll identifier bas prior to
raising the poll tag and holds it valid until a poll return
or burst return is received.
The significance of the poll identifiers is as follows:
(Poll ID bits are shown using logical representation for
active/inactive.)
Poll
identifier
bit§.
~!~g
Q.1ll!!
00000 Poll for
interrupt
level
a
00001
Poll for
interrupt level
1
00010 Poll
for
interrupt level
2
00011 Poll
for
interrupt level
3
00100
Poll for
interrupt level 4
00101
Poll
for
interrupt level
5
00110
Poll for
interrupt
level
6
00111 Poll
for interrupt level
7
01000 Poll
for
interrupt
level 8
01001
Poll
for interrupt
level
9
01010 Poll
for
interrupt
level
10
01011
Poll
for
interrupt
level
1 1
01100 Poll
for
interrupt level 12
01101
Poll
.for
interrupt level
13
01110 Poll
for
interrupt level
14
01111 Poll
for interrupt
level
15
10000
Quiescent
value
10100
Reserved
11000
Reserved
11100
Reserved
lXXOl
Reserved
11X10
Reserved
11111
Poll for
cycle steal
The Poll
identifiers for
interrupt levels
4--15 are not
used
on current processors.
Processor I/O Channel 2-15