w83977ctf Winbond Electronics Corp America, w83977ctf Datasheet - Page 99

• Manufacturer Part Number: w83977ctf
• Description: Winbond I/o
• Manufacturer: Winbond Electronics Corp America

8.0
The W83977EF/CTF uses Compatible PNP protocol to access configuration registers for setting up
different types of configurations. In W83977EF/CTF, 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), CIR (logical device 6)(For
W83977CTF only), 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 these
registers by writing an appropriate logical device number into logical device select register at CR7.
8.1
8.1.1 Extended Function Registers
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:
HEFRAS
PLUG AND PLAY CONFIGURATION
Compatible PnP
0
1
write 87h to the location 3F0h twice
write 87h to the location 370h twice
address and value
-90 -
Publication Release Date: March 1999
W83977EF/ CTF
PRELIMINARY
Revision A1