Keyboard-To-System Interface; System-To-Keyboard Interface - HP Vectra Reference Manual

Keyboard-to-System Interface
When a key is pressed or released on the keyboard, the
corresponding scan code for that key motion is reported over the
HP-HIL to the HP-HIL controller. The HP-HIL controller interrupts
the 80286, which executes the HP-HIL driver to read the scan
codes(s). Inputs from the keyboard are passed to the logical
keyboard driver, where they may be translated, then sent to the
8041 through port 68H. The 8041 then reports the scan code by
placing it in its output buffer, causing an output buffer interrupt
(OBFINT). Then, the scan code may be read by either the BIOS or
directly by an application.
System-to-Keyboard Interface
When the BIOS requires commands to be sent to the keyboard
(i.e., to program the LED's), it sends the byte(s) to port 60H of the
8041. The 8041 acknowledges each byte by returning OFAH to
Port 60H. It then places the command in output Port 69H and
causes an interrupt (HPIND by pulsing -INTHP (P23) low. In
response to this interupt the 80286 executes the logical keyboard
driver, which the reads the command from Port 69H and passes it
on to the HP-HIL driver. The HP-HIL driver translates the command
and sends it to the HP-HIL controller to be sent to the keyboard.
When the command processing is completed, the logical
keyboard driver clears HPINT by writing to Port 6AH, freeing Port
69H.
The following is a figure that shows the HP Vectra keyboard with
the keys numbered and the American legend. Refer to Appendix B
for the international keyboards and the keyboard scan codes.
Keyboard Interface 59