Modern Computers

In modern computers, tiny electronic circuits representing a bit (a binary digit, i.e. a 0 or a 1) replace the balls on the abacus or the gears on the early mechanical machines. The memory of a computer consists of a huge number of these circuits. Data and algorithms are encoded in the memory.

To actually execute the algorithm, you need something else: the Central Processing Unit (CPU). The CPU fetches the instructions that make up the algorithm from the memory, retrieves data from memory, manipulates it and returns the results to the memory afterwards. Modern processors consist of several units with different functions (such as finding memory addresses and performing simple logical operations) which may operate simultaneously.