Using only NAND-gates, you can implement any other logic gates which means you can build an entire programmable computer using only NAND-gates. For example, if

Using only NAND-gates, you can implement any other logic gates which means you can build an entire programmable computer using only NAND-gates. For example, if you send the same signal to both inputs of a NAND gate, you have an inverter, i.e. a NOT-gate. If you place a NOT gate after a NAND-gate then the combination is an AND gate. If you invert both inputs you have an OR gate. Binary addition can be built from AND + XOR, subtraction from addition and so forth. If you pipe the output of an OR-gate back to one of the inputs, then you have a latch which can remember one bit of information. Combine two latches you have flip-flop which can be driven by a clock signal. (The clock signal can be generated by a loop of NOT-gates.) Place flip-flops in parallel you have RAM. See http://nandgame.com http://nandgame.com if you want to try it for yourself.