Atari 800

^ l—
PAT
fc
2
PAl
c
3
PA2
c
*
P«
c
5
PA*
c
«
PW
c
7
PA«
q
S
p^r
9
10
PBI
c
n
PB2
c
12
PBS
c
13
PB«
c
1«
PM
c
1^
PW
c
1«
PB7 17
IS
L
-c
1»
vcc
m
c:
20
MCSU20
40
39
3S
37
3«
33
3*
33
32
31
30
2f
2S
27
2S
23
2*
23
22
21
n**
—
^cAi
^
»•
CA2
—J
,
„„
^
iR^
3
^ iRQB
3
-^
RSI
n-*
M»
>
3
J.
1
3
n
3
3
3^
3-»-
3^
3^
3^
DO
Dt
D2
D3
D*
D3
Dt
07
ENABLE
CSl
CS2
R/ir
Figure 1-7.
PIA Pin
Assignments
Key-In
Key-Out
Integrated
Circuits
These two
*051 (ZlOl
and Z102)
integrated
circuits
are used to
scan the Keyboard
for
input
data on
the
'^00
and 800
Computer Consoles.
The *051
integrated
circuits
are
analog
multiplexers
controlled by
the input lines A, B,
C and X.
Memory
Map
Decoder
The
Memory
Map
Decoder integrated
circuit (Z103)
on the 400/800
Motherboard
is
a
one-of-ten
decoder.
Four
input lines
(pins
12, 13, and U,
and 15)
determine which
output line
is
selected.
The 400/800
Computer
Console uses only
three
of the input
lines
(pins
13, 14,
and
15 and pin 12
being
grounded) for
a total of eight
selected
output
lines
(SO -S7),
Refer to Table
l-I for
the line
selected for
each input
combination.
ATARI
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