Check
Channel
(CKC)
General
Description
Format
(SI)
Condition
Code
Interrupt Action
Notes
Privileged
Instructions
•
The
contents
of
the
general
register
specified by Bl
are
added to
the
Dl
field,
and
the
resultant
sum
identifies
the
input/output
channel to be tested.
This is specified
by
bit
positions
21
through
23
of
the
sum. Only
the
channel
is
tested.
9F
o
7 8
15 16 19 20
31
• 0 - a. The specified selector channel is not busy
and
has
no
interrupts
pending.
b.
The
specified multiplexor channel is not
operating
in
the
burst
mode.
1 - The specified selector channel
has
an
external
device request
inter-
rupt
pending.
2 - a. The specified selector channel is busy
or
has
a
terminating
interrupt
pending.
b. The specified multiplexor is
operating
in
the
burst
mode.
3 - A selector channel is specified
that
is
not
in
the
system.
• Privileged operation.
• 1.
The
address portion
of
this
instruction
specifies
the
channel to be
tested
as
follows:
Bit
Positions
Channel
Specified
21
22 23
0 0
0
Multiplexor
0
0
1 Selector No. 1.
0 1 0
Selector
No.2.
0 1 1 Selector No. 3
1 0 0
Selector No. 4
1
1
0
Undesignated
2.
The
channel address word in
main
memory location 72,
the
channel
block address in
main
memory 76,
and
the channel command
word
are
not used
by
this
instruction.
3.
The
device address
(bit
positions 24
through
31
of
the
sum)
is
not
used
by
this
instruction.
4.
Status
bits (channel
status
byte
and
standard
device byte)
are
not
stored
in
scratch-pad memory by
this
instruction.
5.
Current
operations proceeding in
the
specified channel
are
unaffected
by
this
instruction.
115
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