Atari 400 Technical Reference Manual page 162

Port A Circuit (typical):
A
6520
port
Port
B
Circuit (typical):
+5
(B) 4.7K
1 5
"\
........
;
6 9
Male connector, FRONT view
Pin 8 = Ground
Pin 7
=
Vcc
8+5v
*>
Note: SOmA maximum
total external drain
6520
t----L-""
\ 1 , - - - - 1
I
J
a c
k
on power supply allowed
Port
220
¢.
001
"Trigger" Port Circuit (typical):
CTIA Trig
220
....----WV,....,I,...---------I11
Ja c k
____ -_-_-_-_-_-_-_---1 . ~
001
Software Information
6520 PIA: (This also pertains to all of the following:
**>
Port A control (address
D302)
7 6 5 4 3 2 1 0
o
I
0
I
1
I
1
I
1
I
X
I
0
I
0
I
Wr i t e t his in tot his reg is t e r
+~--port
A Data/Data direction addres
ing control
o =
Data Direction is at 0300
1
=
data
is
at 0300
Port
A
data direction (address 0300)
7 6 5 4 3 2 1 0
X
I
X
I
X
I
X
I
X
I
X
I
X
I
X
I
t
t
t t
t
t t
t
Write this into this register.
Data direction control
for Port
A
1
=
Out
o =
In
OPERATING SYSTEM C016555 -- Section 11
177