W83977EF Winbond Electronics Corp America, W83977EF Datasheet - Page 88

• Manufacturer Part Number: W83977EF
• Description: Description = W83877TF Plus Kbc, GP I/O, Wake-Up, Power Fail Resume ;; Package = QFP 128
• Manufacturer: Winbond Electronics Corp America

8.0
The W83977EF uses Compatible PNP protocol to access configuration registers for setting up
different types of configurations. In W83977EF, there are nine Logical Devices (from Logical Device 0
to Logical Device A with the exception of logical device 4 and 6 for compatibility) which correspond to
nine individual functions: FDC (logical device 0), PRT (logical device 1), UART1 (logical device 2),
UART2 (logical device 3), KBC (logical device 5), GPIO1 (logical device 7), GPIO2 (logical device 8),
and ACPI ((logical device A). Each Logical Device has its own configuration registers (above CR30).
Host can access those registers by writing an appropriate logical device number into logical device
select register at CR7.
8.1
In Compatible PnP, there are two ways to enter Extended Function and read or write the configuration
registers. HEFRAS (CR26 bit 6) can be used to select one out of these two methods of entering the
Extended Function mode as follows:
8.1.1
HEFRAS
Plug and Play Configuration
Compatible PnP
0
1
Extended Function Registers
write 87h to the location 3F0h twice
write 87h to the location 370h twice
address and value
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Publication Release Date: April 2003
W83977EF
Revision 1.1