A combinational circuit is used to control a 6-segment LED (Light Emitting Diode) display of directional
and other symbols as shown below. (1000 represents the + sign, 1001 represents the - sign, 1010
represents a diamond and 1011 represents all segments illuminated). The circuit has four binary
inputs x1, x2, x3, and x4, and six binary outputs a, b, c, d, e and f. The string x3x2x1x0 represents
one of the 12 symbols. (For example, 0101 represents the direction SW.) The circuit works as follows.
If 0011 is input (representing the direction SE), then b = c = d = 1 indicating that the corresponding
segments are to be illuminated whereas a = e = f = 0 indicating these segments are to be darkened
(a) If 0100 is input (direction S), determine each of the following outputs.
1. a =
2. b =
3. c =
4. d =
5. e =
6. f =
(b) Complete the truth table for the output b. The truth table has 16 lines although some of them
will result in dont care conditions.
x3 x2 x1 x0 b
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
1 0 0 1
1 0 1 0
1 0 1 1
1 1 0 0 X
1 1 0 1 X
1 1 1 0 X
1 1 1 1 X
Any help will be appreciated
and other symbols as shown below. (1000 represents the + sign, 1001 represents the - sign, 1010
represents a diamond and 1011 represents all segments illuminated). The circuit has four binary
inputs x1, x2, x3, and x4, and six binary outputs a, b, c, d, e and f. The string x3x2x1x0 represents
one of the 12 symbols. (For example, 0101 represents the direction SW.) The circuit works as follows.
If 0011 is input (representing the direction SE), then b = c = d = 1 indicating that the corresponding
segments are to be illuminated whereas a = e = f = 0 indicating these segments are to be darkened
(a) If 0100 is input (direction S), determine each of the following outputs.
1. a =
2. b =
3. c =
4. d =
5. e =
6. f =
(b) Complete the truth table for the output b. The truth table has 16 lines although some of them
will result in dont care conditions.
x3 x2 x1 x0 b
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
1 0 0 1
1 0 1 0
1 0 1 1
1 1 0 0 X
1 1 0 1 X
1 1 1 0 X
1 1 1 1 X
Any help will be appreciated