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Jd7~
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946261-9701
Bit 8, TILINE Memory Error (ME). This bit is set after completion of one of three disk commands:
write data, write format, or unformatted write, when it has been determined that a memory error
occurred during the time that data was being transferred from the TILINE bus to the disk con-
troller. (This is normally a parity error.)
Bit 9, Data Error (DE). This bit is set during a disk read operation if any of the calculated check
characters (cyclic redundancy characters or CRC) does not match the check character read from the
disk data record(s). This means the CRC did not compare because of a parity error on the disk. All
data transfer operations are terminated after a data error is encountered.
Bit 10, TILINE Timeout Error (TT). This bit is set if the controller addresses a nonexistent memory
address or a slave fails to respond. TILINE timeout causes command termination. The timeout
period is 10
±
2 microseconds from the time master-device active (MDACT) is selected.
Bit 11, ID Word Error (IE). This bit is set when an ID word comparison error occurs during the ID
verification of a read data or write data command. Verification includes comparison of ID words 1
and 2 and CRC checking of the three words. One hardware retry is attempted if an ID error occurs.
If the retry fails, the command is aborted and error status is aborted.
Bit
12,
Rate Error (RE). This bit is set when a timing error is encountered in the transfer of
data between the TILINE master control and the disk interface:
1.
During a read operation, the disk interface exceeds the capacity of the data buffer.
The controller did not transfer the previous word across the TILINE before the next
word is assembled with the buffer being full.
2.
During a write operation, the disk interface empties the data buffer before completing
the writing of a data sector.
Bit 13, Command Timer Timeout (CT). This bit is set when the 200 ±20 millisecond command
timer expires before an operation is completed. The timer acts as a dead-man timer which is reset
when the controller reenters the IDLE loop.
Bit 14, Search Error (SE). Bit 14 is set when the controller does not detect a sync character (>6E)
within one physical sector while attempting to read from the disk. Microcode attempts one retry
before commanding abortion.
Bit 15, Unit Error (UE). The unit error status bit (bit 15) is set when an operation is terminated
because of a disk drive error. The disk status register can be examined by software to determine the
cause of the unit error. The following may cause a unit error:
a.
Unit not ready
b.
Unit off-line
c.
Unit unsafe
d.
Seek incomplete
e.
Write operation is attempted on write-protected unit.
3-9
Digital Systems Division
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