Interface; Keyboard Interface - NEC Advanced Personal Computer System Reference Manual

2.8.2 Interface
The Keyboard connects with a coiled multiconductor cable to the rear of the Main
Unit (see Figure 2-26 and Table 2-11). The cable is a shielded 19-wire design that
includes power(+5 Vdc), grounds, and twelve signal lines. The cable is permanently
attached to the Keyboard.
Figure 2-26 Keyboard Interface
1 3 23 25
1000--------0001
000---------1:] 0
C
2 4 24 26
Processor PCB
2-41