W83877TF Datasheet, PDF (48/154 Pages) Winbond – I/O chip disk drive adapter

W83877TF
2.2.9 Configuration Control Register (CC Register) (Write base address + 7)
This register is used to control the data rate. In the PC/AT and PS/2 mode, the bit definitions are as
follows:
7 6 5 ⁴ 3 ²¹ 0
xxxx xx
X: Reserved
DRATE0
DRATE1
Bit 7-2: Reserved. These bits should be set to 0.
DRATE1 DRATE0 (Bit 1, 0):
These two bits select the data rate of the FDC.
In the PS/2 Model 30 mode, the bit definitions are as follows:
76 5 43 ²¹ 0
XX XX X
X: Reserved
DRATE0
DRATE1
NOPREC
Bit 7-3: Reserved. These bits should be set to 0.
NOPREC (Bit 2):
This bit indicates no precompensation. It has no function and can be set by software.
DRATE1 DRATE0 (Bit 1, 0):
These two bits select the data rate of the FDC.
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Publication Release Date: March 1998
Version 0.61