KBD43W13 Ver la hoja de datos (PDF) - SMSC -> Microchip

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KBD43W13

Keyboard and PS/2 Mouse Controller

SMSC -> Microchip 

STATUS REGISTER (AT MODE)

The status register is an 8-bit read-only register at I/O address hex 64 that holds information about the

status of the keyboard controller and interface. It may be read at any time.

BIT

BIT FUNCTION

DESCRIPTION

0

Output Buffer Full

0: Output buffer empty

1: Output buffer full

1

Input Buffer Full

0: Input buffer empty

1: Input buffer full

2

System Flag

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 is set to 0 after

a power-on reset

3

Command/data

0: Data byte

1: Command byte

4

Inhibit Switch

0: Keyboard is inhibited

1: Keyboard is not inhibited

5

Transmit Time-out 0: No transmit time-out error

1: Transmit time-out error

6

Receive Time-out

0: No receive time-out error

1: Receive time-out error

7

Parity Error

0: Odd parity (no error)

1: Even parity (error)

OUTPUT BUFFER

The output buffer is an 8-bit read-only register at I/O address hex 60. 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 should be read only when the output buffer full bit in the register is 1.

INPUT BUFFER

The input buffer is an 8-bit write-only register at I/O address hex 60 or 64. Writing to address hex 60

sets a flag that indicates a data write; writing to address hex 64 sets a flag that indicates a command

write. Data written to I/O address hex 60 are sent to the keyboard (unless the keyboard controller is

expecting a data byte) following the controller's input buffer only if the input buffer full bit in the status

register is set to 0.

8

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