A) Logic Gates (AND, OR, NOT, NAND, NOR, EX-OR): Review of all logic gates; AND, OR, NOT, NAND, NOR, EX-OR & their truth tables. Appropriate combinations of gates result into an amazing & innovative logical configuration. Basic Logic Gates B) Bit, Nibble and Byte: Bit: The smallest unit of data in a computer is called bit. Nibble: Half a byte that is four bits is called a nibble. Byte: Eight bits forms a byte. C) 1’s Complement & 2’s Complement; their Significance: Let’s consider a number in Hexadecimal ystem: (FB)16 = (1111 1011)2. Further let’s consider complement of its binary form i.e. (0000 0100)2 let add 1 to this number i.e. (0000 0101)2. (04)16 and (05)16 are 1’s complement and 2’s complement of the number (FB)16. The alternative way is FF - FB = 04 is 1’s complement and 04 + 01 = 05 is two’s complement of (FB)16. Further let’s add FB & 05 =100. If we neglect 1, the sum of a number and its 2’s complement is “ZERO” but we know addition of a number to its negative only can lead to zero, hence 2’s complement of a number is negative of the number. Computer does not subtract, it always adds, hence subtraction of number exactly means, addition of its 2’s complement.