Agilent Technologies 6622A Service Manual page 154

Dependency Notation. Dependency notation simplifies
symbols for complex integrated circuit elements by defining
the interdependencies of inputs or outputs without actually
showing all the elements and interconnections involved.
(See Figure A-8 and A-9 for examples of AND dependency
and enable dependency.)
Application of dependency notation is accomplished by:
1. labelling the input affecting other inputs or outputs
with the letter symbol denoting the relationship
involved followed
identifying number, and
2. labelling each input or output affected by the affecting
input with that same number.
If it is the complement of the internal logic state of the
affecting input or output that does the affecting, a bar is
placed over the identifying number at the affected input or
output.
If the affected input or output requires a label to denote its
function, this label shall be prefixed by the identifying
number of the affecting input.
If an input or output is affected by more than one affecting
input, the identifying numbers of each of the affecting
inputs shall appear in the label of the affected one separated
by commas. The left-to-right reading order of these
identifying numbers is the same as the sequence of the
affecting relationships.
Two affecting inputs labelled with different letters shall not
have the same identifying number, unless one of the letters
is A.
If two affecting inputs have the same letter and the same
identifying number they stand in an OR relationship to each
other.
If the labels denoting the functions of affecting inputs or
outputs must be numbers (e.g., outputs of a coder), the
identifying numbers to be associated with both affecting
inputs and affected input or outputs shall be replaced by
another character selected to avoid ambiguity (e.g., Greek
letters).
An affecting input affects only the corresponding affected
inputs and outputs of the symbol.
Note that dependency notation is usually indicated by
numbers. The numbers themselves have no value; they
simply relate two or more points having the same number.
However, sometimes an input or output has a weighted
value (e.g., 1,2,4,8); in these cases a non-numeric symbol
(e.g., ∝ ) may be used to avoid confusion between a
weighted value and the dependency notation.
Eleven types of dependencies are listed below:
A Address - Identifies the address inputs of a memory.
C Control - Identifies an input, such as a timing or
clock input, that produces action, and indicates
which other inputs are controlled by it. Used for
sequential elements (flip-flops, registers), and may
imply more than a simple AND relationship.
A-5
by an appropriately chosen