Flippity Flop

Computer 'logic" is divided into two categories:  Combinatorial logic is based on
Boolean algebra and does not involve feedback of outputs into inputs,
while sequential logic is based on storage components and feeds outputs
of one operation into a later operation.  The most common storage
component is called a multivibrator or flip-flop, and is built around
two "nor" (or "nand") logic gates that feed back into each other.


Multivibrators can be classified as astable in which the outputs of one
gate is "true" (and the other gate is "false") for a period of time,
then that gate switches to "false" and the other gate switches to
"true" for a (possibly different) period of time; monostable, where a
"trigger" input is pulsed (becomes "true" and then "false" after a
short period) one gate stays "true" (and the other "false") for a
period of time, then the other gate stays "true" (and the first gate
"false") until the trigger is again pulsed; and bistable, where one
gate stays "true" (and the other "false") until the trigger for the
other gate is pulsed.

The schematics for some of the types of multivibrators are linked to below,
where a "nor" gate is represented as a chevron (arrowhead) with a
circle between the gate and the output, a "nand" gate as a trapezoid
with a circle between the gate and the output, a "not" gate
(inverter) is a triangle with a circle between the input and the gate,
"1" is the output that is "true" when the component is set, and "0" is
the output that is "false" when the component is set.

Several inputs and outputs are often labelled with a letter, the
traditional meaning of these signals is

C -- Clock input
D -- Data input
J -- Set/toggle input
K -- Reset/toggle input
L -- Latch (capture) input
Q -- Non-inverted (1) output
_
Q -- Inverted (0) output
R -- Reset input
S -- Set input
T -- Toggle input

Astable Multivibrator

Monostable Multivibrator

Bistable Multivibrator

There are several types of bistable multivibrators, which are distinguished by their inputs; some of these types are

R-S Flip-Flop

Toggle or T-type Flip-Flop

Data Latch or D-type Flip-Flop

Master-Slave J-K Flip-Flop