A historical note. The earliest bit-serial processors (EDVAC, EDSAC) were motivated by their serial memory. They stored data as ultrasonic pulses sent through t

A historical note. The earliest bit-serial processors (EDVAC, EDSAC) were motivated by their serial memory. They stored data as ultrasonic pulses sent through tubes of mercury. Since you get the bits out of memory serially, it is easiest to do arithmetic serially too. The Datapoint 2200 desktop computer (whose architecture became the Intel 8008) used a serial processor for similar reasons. Except this time the processor was built from TTL chips instead of tubes and the memory was Intel shift-register memory chips. (Shift register memory could be built cheaper than RAM memory, but with the disadvantage that you had to wait for the bit you wanted to circulate through the shift register.)