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Sense Bit and Name
Explanation
Error Type
Action
Byte 0, bit 0 (Command Reject)
The DAC has received an invalid command code.
Program error
1
Byte 0, bit 0 (Command Reject) and
The DAC has received an invalid seek address.
Program error
1
byte 0, bit 7 (Seek Check)
Byte 0, bit 0 (Command Reject) byte 1, The DAC has received an invalid sequence of commands.
Program error
1
bit 3 (Invalid Sequence)
Byte 0, bit 0 (Command Reject) and
The DAC has received a command that violates the Inhibit
Program error
1
byte 1, bit 5 (File Protected)
Write portion of the File Mask.
Byte 0, bit 1 (Intervention Required)
The specified 2311 unit is:
Equipment error
2
1. Not on line, or
2. Not available for use due to cover interlock open, file
motor off, etc.
Byte 0, bit 3 (Equipment check) and
An unusual condition has been detected in the DAC or the
Equipment error
2
file unit. The condition is indicated by sense-byte 2.
Byte 2, bit 0 (Unsafe) or
A file malfunction has been detected.
Byte 2, bit 4 (Cyclic Code Check) or
Circuitry used to generate the cyclic-code check did not function
properly.
Byte 2, bit 3 (Selected Status) or
Microprogram decode of the status byte yielded self-contradictory
results.
Byte 2, bit 5 (Unselected Status)
The status line from the files is on, but no file has been selected.
Byte 0, bit 4 (Data Check)
The DAC has detected an error in the data field received from
Equipment error
8
the file.
Byte 1, bit 6 (Missing Address Marker)
The DAC has received:
Equipment error
5
1. Two index points without an intervening address marker, or
2. Two successive count fields with equal bit conditions in
bit 0 of the flag bytes.
Byte 0, bit 5 (Overrun)
The DAC access to main storage was suppressed longer than one
Equipment error
3
byte time on the 2311, or a chained CCW was received too late
to be properly executed.
Byte 0, bit 6 (Track Condition Check)
1. A Search, Read, or Write command was attempted on a
Program error
6
flagged defective track (track-condition bit 6 was set to 1 ).
Exceptions: HA and RO operations.
2. Command chaining and multitrack code signals indicate that
operations from an alternate track are to continue on the next
higher-order track.
Byte 0, bit 7 (Seek Check)
The 2311 has been unable to complete the Seek because:
Equipment error
4
1. The access mechanism failed to reposition properly, or
2. The home-address-compare failed after automatic head
switching on a multitrack operation
Byte 1, bit 0 (Data Check in count
The DAC has detected an error in the count field received from
Equipment error
8
Field) and byte 0, bit 4, (Data Check)
the 2311.
Byte 1, bit 1 (Track Overrun)
The index point was detected before writing was completed
Program error
1
Byte 1, bit 2 (End of Cylinder)
An end-of-cylinder was detected before the CCW command
Program error
1
chain was completed while in multitrack mode.
Byte 1, bit 4 (No Record Found) and
Two index points were detected while executing a chain of
Program error
7
not byte 1, bit 6 (missing address
CCWs with no intervening Read or Write operation on the
or
marker)
data field of any record, or Read HA or Read RO CCW.
equipment error
Note: This could be an expected condition on Search
command chains.
Byte 1, bit 5 (File Protect)
The DAC has received a Seek, a multitrack Read, or multitrack
Program error
1
.
search that violated the Seek File Mask.
Byte 1, bit 4 (No Record Found)
Home address or RO cannot be found on the track.
Equipment error
9
and byte 1, bit 6 (Missing Address
Marker)
Figure 2-7. Error Condition Table 2311/DAC (Fart 1 cf 2)
2025 FEMM (7/69) 2-27
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