W83877 Winbond Electronics Corp America, W83877 Datasheet - Page 39

• Manufacturer Part Number: W83877
• Description: Winbond I/O
• Manufacturer: Winbond Electronics Corp America

Status Register 2 (ST2)
Status Register 3 (ST3)
2.2.8 Digital Input Register (DI Register) (Read base address + 7)
The Digital Input Register is an 8-bit read-only register used for diagnostic purposes. In a PC/XT or
AT only Bit 7 is checked by the BIOS. When the register is read, Bit 7 shows the complement of
In the PS/2 mode, the bit definitions are as follows:
DSKCHG
7
,
while other bits of the data bus remain in tri-state. Bit definitions are as follows:
6
7
5
x
6
4
x
5
3
7
x
4
2
6
x
3
1
5
x
x
2
0
4
Reserved for the hard disk controller
During a read of this register, these bits are in tri-state
x
1
3
1 If the FDC detects a CRC error in the data field
MD (Missing Address Mark in Data Field).
1 If the FDC cannot find a data address mark
(or the address mark has been deleted)
when reading data from the media
0 No error
BC (Bad Cylinder)
1 Bad Cylinder
0 No error
SN (Scan Not satisfied)
1 During execution of the Scan command
0 No error
SH (Scan Equal Hit)
1 During execution of the Scan command, if the equal condition is satisfied
0 No error
WC (Wrong Cylinder)
1 Indicates wrong Cylinder
DD (Data error in the Data field)
0 No error
CM (Control Mark)
1 During execution of the read data or scan command
0 No error
Not used. This bit is always 0
x
0
2
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DSKCHG
1
0
US0 Unit Select 0
US1 Unit Select 1
HD Head Address
TS Two-Side
TO Track 0
RY Ready
WP Write Protected
FT Fault
Publication Release Date: January 1996
W83877F
Revision A2