Speaker; P4 Speaker/Keylock Connector - HP Vectra Reference Manual

Speaker
The tones for the HP Vedra PC are produced in a 2 1/4 inch
permanent-magnetic speaker. The speaker can be driven by the
I/O port output bit and/or the 8254A timer/counter's clock out.
Table 2.7
P4 Speaker/Keylock Connector
Pin Assignment
1 Speaker Data
2
+
5 Vdc
3-4
Key
5
Keyboard inhibit
6
Key
7
Ground
Processor Board 39