Commands From The System; Commands To The System - IBM XT 5160 Technical Reference

Commands from the System
Reset (Hex FF)
The system lowers the 'clock' line for a minimum of 12.5
milliseconds. The keyboard then begins to clock bits on the
, data' line. The result is a Reset command causing the keyboard
to reset itself, perform a BAT, and return the appropriate
completion code.
Commands to the System
The following table shows the commands that the keyboard may
send to the system, and their hexadecimal values.
Command
Hex Value
BAT Completion Code AA
BAT Failure Code
FC
Key Detection Error/Overrun FF
The commands the keyboard sends to the system are described
below, in alphabetic order.
BAT Completion Code (Hex AA)
Following satisfactory completion of the BAT, the keyboard
sends hex AA. Any other code indicates a failure of the
keyboard.
BAT Failure Code (Hex FC)
If a BAT failure occurs, the keyboard sends this code,
discontinues scanning, and waits for a system response or reset.
4-26 lOl/102-Key Keyboard