TABLE 17 - STATUS REGISTER 1
NAME DESCRIPTION
End of
BIT NO.
SYMBOL
EN
7
The FDC tried to access a sector beyond the final sector
of the track (255D). Will be set if TC is not issued after
Read or Write Data command.
Cylinder
6
5
Unused. This bit is always "0".
DE
OR
Data Error
The FDC detected a CRC error in either the ID field or
the data field of a sector.
4
Overrun/
Underrun
Becomes set if the FDC does not receive CPU or DMA
service within the required time interval, resulting in data
overrun or underrun.
3
2
Unused. This bit is always "0".
ND
No Data
Any one of the following:
1. Read Data, Read Deleted Data command - the FDC
did not find the specified sector.
2. Read ID command - the FDC cannot read the ID field
without an error.
3. Read A Track command - the FDC cannot find the
proper sector sequence.
1
0
NW
MA
Not Writeable WP pin became a "1" while the FDC is executing a Write
Data, Write Deleted Data, or Format A Track command.
Missing
Any one of the following:
Address Mark 1. The FDC did not detect an ID address mark at the
specified track after encountering the index pulse
from the IDX pin twice.
2. The FDC cannot detect a data address mark or a
deleted data address mark on the specified track.
35
SMSC [ SMSC CORPORATION ]
