50
The
control functions
of
the ports are listed below:
Table 4.3
Port A
Port
Active
Control function
terminal
PA
7
H
Lights LED for
('Rvs]
PA6
H
Lights LED for r-GRPH I
PAs
H
Lights LED for
(sFr
LOcK]
PA
4
L
Reverses B/W
of
entire display screen.
PA
3
H
Stops cassette operation.
PA
2
H
Plays cassette.
PA
1
H
Prepares for
FF
state (prepares for
REW
with L).
PA
0
H
Activates reel motor.
Port B
Port
Control function
Active
terminal
PB
7
H Detects break key during cassette play.
PB
6
Input
terminal for cassette data.
PBs
L Indicates tape is set in the cassette deck.
PB4
L Applies pawl to prohibit writing cassette tape.
PB
3
} Reserved.
PB
2
PB
1
PB
0
H
Indicates fly-back between frame displays.
Port C
Port
terminal
Active Control function
PC
7
Outputs data
to
be written
into
cassette.
PC
6
H
Sets head amp
to
READ state (WRITE with L).
PCs
H
Latches ready state for
FF
and REW.
PC
4
L Starts eject operation.
PC
3
L
Starts IPL.
PC
2
Source pulse
output
sound generation.
PC
1
H
Sets memory in normal state, starting $0000.
PC
0
H
Unconditionally clears the display screen.
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