W83977G Winbond Electronics Corp America, W83977G Datasheet - Page 116

• Manufacturer Part Number: W83977G
• Description: W83877TF plus KBC, CIR, RTC, Pb-free
• Manufacturer: Winbond Electronics Corp America

10.1 Output Buffer
The output buffer is an 8-bit read-only register at I/O address 60H (Default, PnP programmable I/O
address LD5-CR60 and LD5-CR61). The keyboard controller uses the output buffer to send the scan
code received from the keyboard and data bytes required by commands to the system. The output
buffer can only be read when the output buffer full bit in the register is "1".
10.2 Input Buffer
The input buffer is an 8-bit write-only register at I/O address 60H or 64H (Default, PnP programmable
I/O address LD5-CR60, LD5-CR61, LD5-CR62, and LD5-CR63). Writing to address 60H sets a flag
to indicate a data write; writing to address 64H sets a flag to indicate a command write. Data written
to I/O address 60H is sent to keyboard (unless the keyboard controller is expecting a data byte)
through the controller's input buffer only if the input buffer full bit in the status register is _0_.
10.3 Status Register
The status register is an 8-bit read-only register at I/O address 64H (Default, PnP programmable I/O
address LD5-CR62 and LD5-CR63), that holds information about the status of the keyboard controller
and interface. It may be read at any time.
W83977F-A/ W83977G-A/ W83977AF-A/ W83977AG-A
BIT
0
1
2
3
4
5
6
7
Output Buffer Full
Input Buffer Full
System Flag
Command/Data
Inhibit Switch
Auxiliary Device Output
Buffer
General Purpose Time-
out
Parity Error
BIT FUNCTION
0: Output buffer empty
1: Output buffer full
0: Input buffer empty
1: Input buffer full
This bit may be set to 0 or 1 by writing to the system flag
bit in the command byte of the keyboard controller. It
defaults to 0 after a power-on reset.
0: Data byte
1: Command byte
0: Keyboard is inhibited
1: Keyboard is not inhibited
0: Auxiliary device output buffer empty
1: Auxiliary device output buffer full
0: No time-out error
1: Time-out error
0: Odd parity
1: Even parity (error)
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DESCRIPTION