RCA 70/46 Reference Manual page 124

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.
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