Commodore VIC-20 Programmer's Reference Manual page 240

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Handshake Output Mode
Pulse Output Mode
Manual Output Mode
LOW)
Manual Output Mode
HIGH)
(CA2 is
(CA2 is
held
helo
I
I
i
INTERRUPT INPUT MODE:
The CA2 Interrupt flag (IFR bit 0) will be set on a negative
(high-to-low) transition on the CA£ input line. The CA2 interrupt bit
will be cleared on a read or write to PORT A.
INDEPENDENT INTERRUPT INPUT MODE:
As above, the CA2 interrupt flag will be set on a negative
transition on the CA2 input line. However, reading or writing to
PORT A does not clear the flag.
INPUT MODE:
The CA2 interrupt flag {IFR bit 0) will be set on a positive
(low-to-high) transition of the CA2 line. The CA2 flag will be cleared
on a read or write of PORT A.
INDEPENDENT INPUT MODE: .
As above, the CA2 interrupt flag wilE be set on a positive transition
on the CA2 line. However, reading or writing PORT A does not
affect the flag, i
HANDSHAKE OUTPUT MODE; '
The CA2 line will be set low on a read or write to PORT A. It will be
reset high again when there is an active transition on the CA1 line.
PULSE OUTPUT MODE:
The CA2 line is set low for one cycle after a read or write to PORT
A.
MANUAL OUTPUT MODE:
The CA2 line ts held low.
MANUAL OUTPUT MODE:
The CA2 line Is held high.
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