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W83627DHG
Publication Release Date: Aug, 22, 2007
-133- Version
1.4
10.2.8 Digital Input Register (DI Register) (Read base a 7)
The Digital Input Register is an 8-bit, read-only register used for diagnostic purposes. In PC/XT or
PC/AT mode, only bit 7 is checked by the BIOS. When the register is read, bit 7 shows the complement
of DSKCHG#
,
while the other bits remain in tri-state. The bit definitions are as follows:
x
x
x
x
x
x
x
x
0
1
2
3
4
5
6
7
Reserved for the hard disk controller
During a read of this register, these bits are in tri-stat
DSKCHG
In PS/2 mode, the bit definitions are as follows:
1
2
3
4
5
6
7
0
HIGH DENS#
DRATE0
DRATE1
DSKCHG
1
1
1
1
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. See DR register bits 1 and 0 (Data Rate Register (DR
Register) (Write base a 4)) for how the settings correspond to 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
In PS/2 Model 30 mode, the bit definitions are as follows:
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