IBM 2250 3 Manual page 59

APPENDIX B. STATUS-SENSE COMBINATIONS
Conditions
Status Bits Set Sense Bits Set*
General Conditions
1. Initial status response to any command
All bits zero (indicates None
except No-Op or to a Test I/O instruc-
command accepted; for
tion; status not stacked, Test I/O indicates no
status)
2. Initial status response to No Op com- Channel End, Device End
None
mand.
3. Initial status response to any com- Busy plus outstanding
None
mand when the selected 2250 has status
stacked status.
4.
Initial status response to Test I/O in- Outstanding status None
struction when the selected 2250 has
stacked status.
5a, Initial status response to any command
Busy, Status Modifier
None
or to a Test I/O instruction when is-
sued to a selected 2250 while status is
stacked for a nonselected 2250.
5b. After condition 5a occurs, initial status Control Unit End, Busy
None
response to any command or Test I/
0
(uPJess Test I/O), plus
instruction for the 2250 that has stacked outstanding status.
status.
6.
Ending status for commands involving
Device End, Channel End None
data transfer.
7. Ending status for commands not in- Device End, Channel End
None
valving data transfer (e.g., Remove
Cursor), except No Op,
8. Response to Halt I/O instruction when
Device End, Channel End None
the Halt I/O is issued after initial status
and before ending status.
9,
Initial status response to a Sense com-
Device End, Channel End
None
mand when the Sense command is issued
to a 2250 which did not cause the unit check.
Manual Input Conditions
1. Asynchronous status when the alpha-
Attention
None
meric keyboard END or CANCEL key
is pressed.
2. Asynchronous status when any pro-
Attention
None
grammed function keyboard key is
pressed,
3. Light pen detect, which causes buffer
Attention, Unit Check
Light Pen, Buffer
to stop (Enable Switch Detect Opera-
Address
tion, Enable No Switch Detect Opera-
tion, or Permit Detect Interrupts
order active).
Appendixes 61