Model
5340A
Maintenance and Service
5
-
16.
PROGRAM
CONTROL
FLOW
DIAGRAMS
5
-
17.
Figures
5
-
3
and
5
-
4
are flow diagrams showing the sequence of actions required in making
a measurement.
The
A21
Control Board
theory explains how decisions are made in the flow diagram. See Paragraph
4
-
236.
5
-
18.
and selected action number.
Figure
5
-
3
is
a simplified version of Figure
5
-
4.
Figure
5
-
4
lists
three sets
of
numbers: the program address, the selected test number,
5
-
19.
The program address
is
the 5
-
bit binary number placed to the right of the rectangle and
diamond symbols in the diagram. These
5
bits are the inputs to
ROM’s
A21U3
and
A21U4.
When
an
HP
10528A
Logic Clip is installed on
A21U4,
the program address appears on pins
10
through
14.
Note that the logic clip diagram shown on Figure
5
-
4
uses circles to designate these
pins.
5
-
20.
Inside each rectangle
is
a decimal number that indicates what action
is
required and this
corresponds to the action of
A21U13.
This number can be read in binary on pins
5, 6,
7,
and
9
of
A21U4.
These pins have binary weights
1, 2, 4,
and
8,
respectively.
To
determine the required
action, add the binary weights of the pins activated.
5
-
21.
For example, if
A21U4
pins
5,
6,
and
7
were
TTL
High (indicated by
a
lit
LED),
the re
-
quired action is
(1
+
2
+
4)
=
7.
Note that the four pins designating action data are diagrammed
as rectangles in the logic clip diagram to correspond with the rectangles of the flow diagram.
5
-
22.
Decision points are indicated by diamonds and the associated decimal number indicates
the test required. This number, which corresponds to the number in
A21U12,
can similarly be
read on the logic clip on the pins designated with diamonds in the diagram. Note that this cor
-
responds to the diamond shapes on the flow chart.
5
-
23.
It may be possible to single step the
5340A
through the flow diagram to check for proper
branching. Refer to
A21
Troubleshooting.
i
I
5
-
14
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