Description - HP 3455A Operating And Service Manual

Model 3455A
e. The main controller next checks to see if one of the
math functions have been selected. The math functions pro-
xX —Z
vide either a scaled answer ( ), where x is the measure-
ment answer and y and z are values entered by the opera-
X
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
WVERTER
THEORY OF OPERATION
Section VII]
into them. If the buffers are active the controller bypasses
this step.
g. The main controller loads the final answer in the dis-
play buffers and returns to the start of the program.
8-118. Circuit Description.
8-119. 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
OUTPUT
LATCHES
DEVICE
SELECT
Figure 8-36. Simplified Output Circuit.
8-23