Final answer:
A computer designed to execute programs extremely rapidly is a supercomputer, used for tasks that require massive computational power.
Step-by-step explanation:
A computer that is designed to execute a few programs extremely rapidly is known as a supercomputer. Supercomputers represent the pinnacle of processing power, often used for a variety of complex tasks that require vast amounts of computations, such as weather prediction, scientific simulations, and cryptanalysis. These machines are vastly different from minicomputers, which support multiple users but have less computing power than mainframes, and from personal computers or PCs, which became widely available in the 1980s thanks to advancement in microprocessors and microchips.