Q Draw the circuit to check a PALINDROME number of even bits.
Ans: Palindrome number (in bits) is the number which is same whether seen from the first and the last bit. E.g. 1001, 0110, 0000, 1111 in 4 bits
So to check this we need to have same value of bit at 1^{st} bit and 4^{th} bit, 2^{nd} and 3^{rd} bit position for a 4bit number. For a 6bit number we need to have same bits at 1^{st} and 6^{th} bit, 2^{nd} and 5^{th} bit, 3^{rd} and 4^{th} bit positions.
Hence to check whether bits in different pairs have same value we need to have XNOR gate and then AND them to see whether all pairs satisfy the condition.
So we have the general circuit as next:
We can verify this for a 4bit number as done next.
So Kmap for that is as
And hence we see that we need to XNOR the corresponding bits and then take AND of all outputs of XNORs
