4 variables

Input interface

					Y			Reset	Highlight groups
	A	B	C	D	0	1	x		SOP
0	0	0	0	0					POS
1	0	0	0	1					Quine-McCluskey Method (SOP)
2	0	0	1	0
3	0	0	1	1					CSS circuit drawing
4	0	1	0	0					ASCII circuit drawing
5	0	1	0	1
6	0	1	1	0
7	0	1	1	1
8	1	0	0	0				Try Tab and arrow keys for keyboard input.
9	1	0	0	1
10	1	0	1	0
11	1	0	1	1
12	1	1	0	0
13	1	1	0	1
14	1	1	1	0
15	1	1	1	1