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Bit
Designation
Interpretation
7
C/P Compare
Set in 6250 BPI when hardware logic detects an internal
parity error.
Set in seven-track NRZI if correct parity (odd or even) is
not maintained by the tape control as follows:
a. With translator and data converter both off if parity
within a byte changes within the tape control during
read or write.
b. With data converter on and translator off on read
operations if the parity of a group of four BCD
characters changes within the tape control.
c. With data converter on and translator off during
write operations if the parity of a group of three
EBCDIC bytes changes within the tape control.
Notes:
1.
Bus Out Parity Error or MTE can cause a C
Compare error.
2. Data Converter Check blocks C Compare if DCC
occurs first.
Sense Byte 4
Bit
Designation
Interpretation
0
MP Hardware Error
MP Hardware Error is set whenever an MP 1 or MP 2
Hardware Error occurs as defined in sense bytes 11 and
12.
Reject Tape Unit
Reject Tape Unit is set if the selected tape unit dropped
.
ready' during execution of a tape motion command .
2
Tape Indicate
Tape Indicate is set whenever the end-of-tape marker is
sensed during a forward tape operation.
3
Write Trigger YRC
Write Trigger YRC is set if the byte written by the write
triggers has incorrect parity.
4
Spare
5
Loop-Write-To-Read
Present when the last command was a
Loop-Write-To-Read.
6
Tape Unit Check
Present when Unit Check is present in the tape unit
sense.
7
Reserved for RPQ
Sense Byte 5
Bit
Designation
Interpretation
0
New Subsystem
Always zero on 3803-2/3420 subsystem.
New Subsystem
Always present on 3803-2/3420 subsystem.
2
Write Tape Mark Check
Present when a tape mark is not written properly.
3
ID Burst Check
Present if the 6250 BPI or PE identification burst is not
written correctly off load point. May be on if byte 8, bit
4 is on.
4
Start Read Check
Present when beginning of data is not recognized.
5
Partial Record
Present when IBG appears before end of data is
recognized.
6
Postamble Error
Present when a postamble error is detected.
7
Reserved for RPQ
Section 4: Status and Sense Information
43
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