Atari 800

PIA ADDRESSES
WRITE READ
Address Name
Descri__2_tion Name
Description
D3FF
I
Repeat
as
shown below many times
D304
D303
PBCTL PORT B CONTROL PBCTL
Same
as
write
D302 PACTL PORT A CONTROL
PACTL Same as write
Direction Register
PORTB If PBCTL Bit 2-0
PORTB
Same
as write
D301 (otherwise}
\
Jack 2 & Jack 3
Jack 2 & Jack
3
PORTB If Direction Bits PORTB
If Direction Bits
Are 1
*
Are 0
*
Direction Register
PORTA
If PACTL Bit 2=0 PORTA
Same
as write
D300
(Otherwise)
Jack 0 & Jack 1
Jack 0 & Jack 1
PORTA
If Direction Bits
PORTA If Direction Bits
Are 1 *
Are 0
*
* NOTE: Output data is retained in Jack Output Registers.
If direction bits are true, a read of the jacks
will read old data from these registers.
V.4
.