w83977eg Winbond Electronics Corp America, w83977eg Datasheet - Page 43

• Manufacturer Part Number: w83977eg
• Description: Winbond Isa I/o W83977ef W83977eg
• 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
ofDSKCHG#
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.
HIGHDENS#(Bit 0):
0
1
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
x
7
4
1
6
x
3
1
5
x
x
2
1
4
Reserved for the hard disk controller
During a read of this register, these bits are in tri-stat
x
1
W83977EF-AW/W83977EG-AW
1
3
x
0
2
-41-
DSKCHG
1
0
DRATE1
HIGH DENS#
DRATE0
DSKCHG
Publication Release Date: Apr. 2006
Revision 1.2