“I know there's a proverb which that says 'To err is human,' but a human error is nothing to what a computer can do if it tries.” ― Agatha Christie, Hallowe'en Party


Early Computing

Handmade Bits

For the earliest computers, CPU architectures and CPUs were not defined as discrete components of a computer. Instead, technicians would change switches inside a computer so that the program being computed was hard wired into the physical machine. The layers of abstraction commonplace in modern computers were not to be found. This process was both laborious and troublesome, taking weeks to enter a single program into a computer’s memory.



As the 1950s progressed, core concepts integral to how a CPU operates was developed by several different companies, including IBM and Unisys. This mob of companies developed such ideas as index registers. As this initial period of computer use ended, the idea of the CPU architecture as a way for programs to communicate with hardware was not yet defined. That type of innovation belonged to the next period, in the Swinging Sixties.

ENIAC, the first machine that fits the modern definition of a digital computer.