Appendix 1-4 Interfaces Rev.A
Confidential
Keyboard/Mouse Port
The 80C42 compatible circuit in the M1543 chip on the mother board contols the data from the
PC keyboard through the 80C31 processor on the POS board. Any mini-DIN type keyboard with
PC/AT compatibility can be connected directly to the keyboard connector. The PS/2 mouse
must be connected with a branch cable. Assignments of signals are shown below. The electric
current capacity of the attached keyboard must be 500mA or less.
A1-5 Keyboard/Mouse connector
There are the following restrictions on the keyboard interface.
EFh and F1H are the key definition commands for the 84 keyboard unit, and a series of data
following those two commands are not sent to the external keyboard. (You may send the
data using PKMODE command.)
Unless 130 or more microseconds elapses after data transmission to the external keyboard,
the data from the keyboard cannot be received. Also, the response from the external
keyboard to the command must be given within 15 milliseconds.
Table A1-3 Assignment of keyboard/mouse port pin assignments (VR board CN2)
No. Signal name I/O Description
1 KBDATA I/O Keyboard data signal
2 MSDATA I/O Mouse data signal
3GND-- Ground
4+5V-- +5V of electrical power
5 KBCLK I/O Keyboard clock signal
6 MSCLK I/O Mouse clock signal
12
34
56
KBCLK
IM -> K/B K/B -> IM
KBDATA Transmitted Data Receive Data