RCA 70/46 - Condition Code

Condition Code
(Cont'd)
Channel Status Byte
Condition
Code
o
1
2
3
Condition
Code
0
1
2
3
Input/Output Operation
T est Device Instruction Condition Code Settings
Meaning
The device control electronics and the device are available.
Note: There may be pending interrupts on the multiplexor channel
that would prohibit a burst mode operation being initiated.
This condition code indicates that the standard device byte has been
stored in the channel registers for the specified channel. The channel
status byte is never stored by this instruction.
The standard device byte is stored under the following conditions:
1. The specified device control electronics on the multiplexor chan-
nel indicates that a device request interrupt pending condition
is present. The external device request interrupt pending bit in
the standard device byte is set.
2. The specified device is busy but the device control electronics
is not busy (i.e., tape rewinding, off-line seek to a random access
device). The device busy bit in the standard device byte is set.
3. The specified device is inoperable. The device inoperable bit in
the standard device byte is set.
1. A selector channel is specified that is busy.
2. A selector channel is specified that has an interrupt pending
(termination or external device request).
3. The multiplexor channel is specified and it is operating in burst
mode.
4. The multiplexor channel is specified and the addressed device
control electronics is busy with addressed or non-addressed device.
5.
The multiplexor channel is specified and the addressed device
control electronics has a termination interrupt pending.
1. A selector channel is specifiEld which is not on the system.
2. The specified device control electronics is inoperable.
3. A device is specified that is :not in the system.
Check Channel Instruction Condition Code Setting
Meaning
1. The
specified selector channel is not busy and has no interrupts
pending.
2. The specified
mUltiplexor channel is not operating in the burst
mode.
The specified selector channel has an external device request inter-
rupt pending.
1. The specified selector channel is busy 01' has a terminating inter-
rupt pending.
2. The specified multiplexor is operating in the burst mode.
A selector channel is specified that is not in the system.
• The channel status byte is stored in Channel COlnmand Register-II
(bit positions 8 through 15) for the appropriate channel. It contains infor-
mation concerning the status of the channel when a channel interrupt
occurs, or at the completion of a Start, Halt or Test Device instruction if
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