W83977EG-AW Datasheet, PDF (43/142 Pages) Nuvotem Talema – These products are not designed for use in life support appliances

W83977EF-AW/W83977EG-AW
5.2.8 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
ofDSKCHG#, while other bits of the data bus remain in tri-state. Bit definitions are as follows:
76 54321 0
xxxxxx x
x ^{Reserved for the hard disk controller}
During a read of this register, these bits are in tri-stat
DSKCHG
In the PS/2 mode, the bit definitions are as follows:
765 43
11 1 1
21
0
HIGH DENS#
DRATE0
DRATE1
DSKCHG
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):
0 500 KB/S or 1 MB/S data rate (high density FDD)
1 250 KB/S or 300 KB/S data rate
Publication Release Date: Apr. 2006
-41-
Revision 1.2