Keyboard Interface - NEC PC-8201 Service Manual

3 . 1 . 7 Keyboard Interface
The keyboard is sensed by a software scan.
It transmits low signals (OUT
-
B9. OUT
BA)
to Port A or Port B a t 81C55, and senses the depressed key by IN E8.
*
Key board Interface Port
I
1 0 1 1 1 1 0 0 1 OUT B9
I
OUT BA
PA7- PA0
0 0 0 0 0 0 0 1
0 0 0 0 0 0 1 0
0 0 0 0 0 1 0 0
0 0 0 0 1 0 0 0
0 0 0 1 0 0 0 0
0 0 1 0 0 0 0 0
0 1 0 0 0 0 0 0
1 0 0 0 0 0 0 0
PB7 -PBO
0 0 0 0 0 0 0 1 CAPS --SHIFT
Key
L - z
K - A
I
- Q
A /
-
0
8(
-
1'
PAST
, 9.)
INS
-
DEL
BS
STOP
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I