Serial computers require much less hardware than their bit-parallel counterparts[1] 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[2] which can serve niche purposes where the 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.
^Miller, Raymond E. (1965). Switching Theory – Volume 1: Combinational Circuits. Vol. 1 (Second printing, March 1966, of 1st ed.). John Wiley & Sons, Inc. pp. 44–47. LCCN65-14249.
^Whitney, Thomas M. (1975). "Part I. Basic Computer Architecture. / Chapter 3. Introduction to Calculators: / 3-5. Example Systems / The Hewlett Packard HP-35". In Stone, Harold Stuart (ed.). Introduction to Computer Architecture. Computer Sciences Series (1 ed.). Science Research Associates, Inc. (SRA). pp. 118–135 [123–135]. ISBN0-574-18405-8. LCCN75-14016. ark:/13960/t8pc40t3q. Order-Code 13-4005. Retrieved 2023-09-29. p. 124: […] The HP-35 is a totally serial computer. The adder is a BCD serial type […] The serial structure means less integrated circuit area must be allocated to interconnection lines and gating functions and an interesting trade off occurs. A bit-serial, digit-serial architecture is inherently one fourth the speed of a bit-parallel digit-serial structure […] But the basic clock rate for a bit-serial structure can sometimes be increased since additional area can be allocated for larger integrated devices that are necessary for greater speed. In the HP-35, the execution time of the most complex functions is under one second, while the serial architecture permits an increased circuit complexity. […] Instructions in the HP-35 are transferred serially from the active read-only memory to the arithmetic and control circuits and to other ROMs if present. […]
Hartley, Richard I.; Parhi, Keshab K. (1995). Digit-Serial Computation. The Kluwer International Series in Engineering and Computer Science (1 ed.). Norwell, Massachusetts, USA: Kluwer Academic Publishers. ISBN0-7923-9573-5. SECS316. (xiv+306 pages)