 Originally, all electronic computers were serial (single-bit) computers.The first electronic computer that was not a serial computer—the first bit-parallel computer—was the 16-bit Whirlwind from 1951.From the advent of very-large-scale integration (VLSI) computer chip fabrication technology in the 1970s until about 1986, advancements in computer architecture were done by increasing bit-level parallelism, as 4-bit microprocessors were replaced by 8-bit, then 16-bit, then 32-bit microprocessors.