w83977atg Winbond Electronics Corp America, w83977atg Datasheet - Page 46

• Manufacturer Part Number: w83977atg
• Description: W83877tf Plus Kbc, Gp I/o, Wake-up, Fir, Cir, Pb-free
• Manufacturer: Winbond Electronics Corp America

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
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
x
4
1
6
x
3
1
5
x
x
2
1
Reserved for the hard disk controller
During a read of this register, these bits are in tri-stat
4
x
1
1
3
x
0
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2
DSKCHG
1
W83977ATF/W83977ATG
0
DRATE0
DRATE1
HIGH DENS
DSKCHG