Sharp MZ-700 Series Owner's Manual page 133

4.3.1 Signal system of the 8255
The 8255 outputs keyboard scan signals, input key data, and controls the cassette tape deck and cursor
blink timing.
8 2 5 5
Port Terminal
I/O
Active state
Description of control Name of signal
PA
(SEOOO)
PA
0
PA,
PA
2
PA
3
PA
7
OUT
H
H
H
H
L
Keyboard scan signals
Resets the cursor blink timer.
556 RST
PB
(SEOOl)
PB
0
PBI
PB
2
PB
3
PB
4
PB
S
PB
6
PB
7
IN
L
L
L
L
L
L
L
L
Key scanning data input signals
PC*
(SE002)
PC,
PC
2
PC
3
PC
4
PCs
PC
6
PC
7
OUT
OUT
OUT
IN
IN
IN
IN
Cassette tape write data
Inhibits clock interrupts.
Motor drive signal
Indicates that the motor is on.
Cassette tape read data
Cursor blink timer input signal
Vertical blanking signal
WDATA
INTMSK
M - O N
MOTOR
RDATA
556 OUT
VBLK
* Each output data bit can be independently set or reset.
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