The
elemental building blocks of all
hardware. Includes
combinational logic and
sequential logic. Examples of combinational logic gates are:
NAND,
NOR,
AND,
OR,
XOR,
XNOR,
NOT,
AOI, and
OAI. Sequential gates typically are the
D flip-flop, the
T flip-flop, the
SR latch, and the
D latch, but there are many
variations of
set,
reset,
preset,
clear and so forth, as well as
enable, and
scan.
Logic designers either
design their circuits from scratch using these
primitives, or they use a hardware description language like
Verilog and very expensive software from
Synopsys (or
Ambit) to
synthesize the appropriate
logic.