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Model
34SSA
THEORY
OF OPERATION
Section
VUl
e.
The
main
controller
next checks
to see
if
one of
the
math
functions
have been
selected.
The math
functions
pro-
X
-
z
vide either a scaled
answer
(
y
),
where
x
is
the
measure-
ment
answer and
y
and
z are values
entered
by
the opera-
x
-
y
tor,
or
a
percent
error
answer
(
—
~
—
x
100),
where
x
is
the
measurement answer and y
is
a^
reference value entered
by
the operator.
If
the
math
function has
been
selected,
the
main
controller
computes
the
math
answer.
f.
The
main
controller
next checks
to see
if
the
HP-IB
buffers
are active
(outputting data to the
bus).
If
the
HP-IB
buffers
are
not
active,
the
main
controller loads
the
answer
into
them.
If
the buffers
are active
the
controller
bypasses
this step.
g.
The
main
controller loads the
fmal answer
in
the
dis-
play buffers
and
returns to the
start
of
the
program.
8-1 18. Circuit Description.
B-119.
ROM
Circuit.
The
main
controller
uses
three
ROM's
to store the
programs
necessary to control the
var-
ious functions
and
operations
of
the voltmeter.
Each
ROM
is
capable
of
storing
2048,
eight
bit
"words" of program
information
and
is
divided
into
two
"pages" of
1024 words
8-23
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