A serial computer is a computer typified by bit-serial architecture – i.e., internally operating on one bit or digit for each clock cycle. Machines with serial main storage devices such as acoustic or magnetostrictive delay lines and rotating magnetic devices were usually serial computers. Serial computers require much less hardware than their bit-parallel counterparts which exploit bit-level parallelism to do more computation per clock cycle. There are modern variants of the serial computer available as a soft microprocessor which can serve niche purposes where size of the CPU is the main constraint. The first computer that was not serial and used a parallel bus was the Whirlwind in 1951. A serial computer is not necessarily the same as a computer with a 1-bit architecture, which is a subset of the serial computer class. 1-bit computer instructions operate on data consisting of single bits, whereas a serial computer can operate on N-bit data widths, but does so a single bit at a time.

Serial machines

Massively parallel

Most of the early massive parallel processing machines were built out of individual serial processors, including: