HP Compaq dx 7200 and dc7600 Personal Computers, Technical Reference Guide, 1st Edition

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Keyboard
C.2.5 Keyboard Commands
Table C-1 lists the commands that the keyboard can send to the system (specifically, to the
8042-type logic).
Note:
[1] Modes 2 and 3.
[2] Mode 1 only.
Table C-1.
Keyboard-to-System Commands
Command Value Description
Key Detection Error/Over/run 00h [1]
FFh [2]
Indicates to the system that a switch closure
couldn’t be identified.
BAT Completion AAh Indicates to the system that the BAT has been
successful.
BAT Failure FCh Indicates failure of the BAT by the keyboard.
Echo EEh Indicates that the Echo command was received by
the keyboard.
Acknowledge (ACK) FAh Issued by the keyboard as a response to valid
system inputs (except the Echo and Resend
commands).
Resend FEh Issued by the keyboard following an invalid
input.
Keyboard ID 83ABh Upon receipt of the Read ID command from the
system, the keyboard issues the ACK command
followed by the two IDS bytes.