W83977G Winbond Electronics Corp America, W83977G Datasheet - Page 44

• Manufacturer Part Number: W83977G
• Description: W83877TF plus KBC, CIR, RTC, Pb-free
• Manufacturer: Winbond Electronics Corp America

Status Register 3 (ST3)
5.2.8
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 (Bit 7):
This bit indicates the complement of the DSKCHG input.
Bit 6-3: These bits are always a logic 1 during a read.
DRATE1 DRATE0 (Bit 2, 1):
These two bits select the data rate of the FDC. Refer to the DR register bits 1 and 0 for the settings
corresponding to the individual data rates.
0
1
HIGH DENS (Bit 0):
DSKCHG
W83977F-A/ W83977G-A/ W83977AF-A/ W83977AG-A
500 KB/S or 1 MB/S data rate (high density FDD)
250 KB/S or 300 KB/S data rate
Digital Input Register (DI Register) (Read base address + 7)
,
while other bits of the data bus remain in tri-state. Bit definitions are as follows:
7
x
6
x
5
7
7
x
4
6
1
6
x
3
5
1
5
x
x
2
4
1
Reserved for the hard disk controller
During a read of this register, these bits are in tri-stat
4
x
1
3
1
3
x
0
2
-36
2
DSKCHG
1
1
0
0
US0 Unit Select 0
US1 Unit Select 1
HD Head Address
TS Two-Side
TO Track 0
WP Write Protected
FT Fault
RY Ready
DRATE0
DRATE1
HIGH DENS
DSKCHG