design a 4-bits synchronouus counter using D Flip-Flops an 16X4 bit ROM that cant generate any arbitrary counting sequence. What are the restriction on the counting sequence? Give the ROM contents for the following sequences:
12, 13, 14, 15, 5, 6, 7, 0, 1, 2, 3, 4, 11, 10, 9, 8, 12, 13 ...