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SCHOTTKY BIPOLAR
8212
8080
ADDRESS
.:...
BUS
(See
Note 1)
A
O
-'
A
1
--+-
A
2
--+-
8205
~
~
E
1
::=:-
~
--0
E
2
::-
Vee
-
..
E_
3
__
..
I/O
DEVICE
SELECTOR
ST;~;T:¢
ST:
212
tt:7:::~~llllltnn~
8212
=>
~:~~T
~
;:N~~-
:IIII[
_~L~ee?
INP
--
......
----t-t-t-t-t-+--+-t------------+-6
STATUS
BITS -
STROBE
2
---.
STB
INPUT
~
PORT 2 L-Y 8212
8212
~
OUTPUT
W PORT 2
~
CLR
~
OUTPUT
W PORT 3
~
OUTPUT
W PORT 4
~
OUTPUT
hi"
PORT 6
8212
Ill::
ttm::zb
ill\:,z:Zht~
y
~f
y
:111
_~L:ee
y
STROBE 4
--.
STB
INPUT
~
PORT 4
L.-,I
8212
:::::
ST;~;;~¢
ST:
212
~m:~~j!II!:w::7::~3
8212
t>
~~~~~T
~
~~~~_.
I!!!!
-~~e
I
ST;;;;T:
¢
ST:2~
::::::::::::::::::::::~~
II::::::::::::::::::::?
8212
.......
------<=.11
INT
CLR
~~
:~:~:
~
CLR
1
G~D
L-_
\l~\l
-~
Vee
I
I
PRIORITY
ENCODER &
INTERRUPT
GENERATING
LOGIC
CIRCUITS
(USER DESIGNED)
_
OUT
----t------r-t-t-t-t----ir+-t-----------+--+----1~:::::f_4
ST;;;;T:::
ST:
212
m::ili::~Jtmm:~
8212
_----L.-,I-<~J11INT
CLR
0-<1
-Y[[~\!
.:
CLR
. 1
G~D
L-_
:::[:[
,_-.J
Vee
Y
8212
INTERRUPT
INSTRUCTION
PORT (RST)
BUFFERED
DATA
BUS
8212
+--.s>
GND
u
BI-DI
RECTIONAL
BUS
DRIVER
INT
--------004----------1
r-
-,
I I
I I
I
Vee
I I
I I
I I
~ I 0
'1IO-++++----4~
~
I 1
IO-++++-.-.....~
~
I 2
1O-++++---oIt--
.....
~
H 3
IO-++++-.....-~
-
~
4
1O-++++---oIt---------<:::JIINT
CLR
~
-
--I
5
1O-++++---oIt--_
=:
~
1
G~D
L-~
................ I I
v~e
I:
i
GND
I I
I I
L
__
II_
..I
INT
-----..----t:
ACK
8080
--...J..
D:J:~!I.
8212
DalN-t?!NrJ
I I
STROBE 7
---+-
STB
8212
8212
~OUTPUT
W PORT 7
SYSTEM--.....-
RESET
Note 1. This
basic
I/O
configuration for the
8080
can
be
expanded to 256 input
devices
and
256 output
devices
all
using
8212
and
the appropriate decoding.
5-108