HP
5384A and
HP
5385A
Service
8-50.
Figure 8-3 shows that unless otherwise
quali-
fied by dependency notation,
an
input
to the
common-
control
block
is
an
input
to
each
of
the elements
below
the
common-control
block.
output
element. Its distinctive visual feature
is
the
double
line
at its top. In
addition
the
common-output
element
may have
other
inputs
as
shown
in
Figure 8-4.
The
function
of
the
common-output
element
must
be
shown by use
of
a general
qualifying
symbol.
COMMON·CONTROL
BLOCK
I
a
a
b
c
b
c
d
d
COMMON·OUTPUT
a§d
8
ELEMENT e
E
b I
(must, like other elements,
-..__
b
have a
qualifying symbol
to
~
denote
Us
logic function). c g
Figure 8-3.
llfustration
of
Common-Control
Block
8-51. A
common-output
depending
on
all elements
of
the
array can be shown
as
the
output
of
a
common-
Figure 8-4. llfustration
of
Common-Output
Element
8-6
SYMBOL
&
~1
=1
2k
2k+1
1
=or-
X/Y
MUX
DMUX
or
DX
I:
P-Q
CPG
COMP
ALU
1
Table 8-2. General
Qualifying
Symbols
DESCRIPTION
AND
gate
or
function.
OR gate
or
function.
The symbol
was
chosen
to
indicate
that
at
least
one
active
input
is
needed
to
activate
the
output.
Exclusive OR.
One
and
only
one
input
must be active
to
activate
the
output.
logic
identity.
All
inputs
must stand
at
same state.
An
even
number
of
inputs
must be active.
An
odd
number
of
inputs
must be active.
The
one
input
must be active.
A
buffer
or
element
with
more
than usual
output
capability (symbol
is
oriented
in
the
direction
of
signal flow).
Schmitt
trigger;
element
with
hysteresis.
Coder,
code
Converter
(DEC/BCD,
BIN/OCT,
BIN/7-SEG, etc.).
Multiplexer/data
selector.
Demultiplexer.
Adder.
Subtracter.
look-ahead
carry generator.
Multiplier.
Magnitude
Comparator.
Arithmetic
logic
unit.
Retriggerable monostable.
Nonretriggerable
monostable
(one-shot)
EXAMPLE
SN7400
SN7402
SN7486
SN74180
SN74180
*
SN7404
SN74S436
SN74lS18
SN74lS347
SN74150
SN74138
SN74lS385
SN74lS385
SN74182
SN74LS384
SN74lS682
SN74l5381
SN74l5422
SN74121
*Not
all
of
the
general qualifying symbols have
been
used
in
this
book,
but
they
are
included
here
for
the
sake of completeness.
•
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