SR Flip Flop:
The
SR Flip Flop is a simple
latch that takes in two
inputs, and holds (latches) the input (S) on the output line (Q). The complement of Q, aka Q', is also latched. The inputs of S=0 and R=0 does not have an affect on the current state. The undefined state can be eliminated by changing the
SR Flip Flop to a
D Flip Flop
A
SR Flip Flop can be constructed out of two nor
gates with thier outputs coupled with the
opposite gates input.
SR Gate State Table using 2-input Nor Gates :
S R Q Q' State
-----------------------------------------
1 0 1 0 Set State
0 0 1 0
0 1 0 1 Reset State
0 0 0 1
1 1 0 0 Undefined State
SR Gate Diagram using two 2-input Nor Gates :
________
R-------| |
| Nor |-----X------------------Q
| | |
---|_______| |
| |
| |
|________________C_________
| |
| |
----------------- |
| ________ |
|--| | |
| Nor |---------------X-------Q'
| |
S-------|_______|
Diagram Notes:
Inputs: S, R
Outputs: Q, Q'
Other:
C= The "C" in the diagram means the travelling
connection hops over the wire it would otherwise
cross into
X= The "X" is where one wire attaches to another wire