Signetics Programmable Logic Devices - Al Kossow's Bitsavers

Signetics Programmable Logic Devices
Signetics Programmable Logic
Introduction
TRANSITION TERMS
Po------------~
I L.. _________.I
I
COMPLEMENT ARRAY
As indicated in Figure 28, the single Complement
Array gate may be used for many states
of the state diagram. This happens because all
transition terms linked to the OR gate include
the present state as a part of their conditional
logic. In any particular state, only those transition
terms which are a function of that state are
enabled; all other terms coupled to different
states are disabled and do not influence the
output of the Complement Array. As a general
rule of thumb, the Complement Array can be
used as many times as there are states.
DIRECT {
T3 = Po{PoX + poy)
T 3 ;; Po[Po(X + V)]
T3 = Po[Po + (X + V)]
T3 ;; a + Po(X + Y)
T3 =Po(X.V)
COMPLEMENT
a. Typical State Sequence
b. Complement Jump
Figure 27. a. X And Y Specify the Conditional Logic for Direct Jump
Transition Terms T1 and T2. The Complement Jump Term T3 is True Only
When Both T 1 and T 2 are False. b. Note that the Complementary Logic
Expression for T 3, T 1 + T 2, Corresponds Exactly to the Logic Structure of the
Complement Array.
January 1990 25