I understand how transistors and basic computer hardware work, but I'm having trouble understanding how humans originally created a system that machines could use to store data and perform instructions. How did we decide that certain electrical states or binary values should represent numbers, characters, or operations? Was there a standard or guideline, or were these meanings chosen by the designers of each computer? I'm especially curious how we progressed from simple circuits to programmable computers and modern programming languages.
5 Answers
The key ideas came from logic and computation theory. Researchers showed that complex algorithms could be expressed as combinations of simple logical operations, and engineers built circuits that performed those operations. There was no moment when machines learned to understand information; humans designed conventions and hardware together, then gradually added abstractions that made the system easier for people to use.
Early calculating machines often had their operations built directly into the hardware, so they weren’t programmable in the modern sense. Programmability came from storing instructions as data and building hardware that could fetch and execute those instructions. From there, layers of abstraction developed: machine code led to assembly, then higher-level languages, libraries, and operating systems. Each layer hides more of the lower-level details.
Computers don’t actually understand information. They’re physical systems designed to respond to electrical signals in specific ways. A high or low voltage can represent 1 or 0, and transistors can be combined into logic gates such as AND, OR, and NOT. Larger circuits built from those gates can perform calculations, store bits, and control other circuits.
A useful analogy is a light switch or an AND circuit. The switch doesn’t understand “on” or “off”; its physical arrangement simply allows current to flow or blocks it. A computer works the same way at a much larger scale. People choose an interpretation for a pattern—such as treating eight bits as a character or an instruction—but the hardware only carries out the behavior it was physically designed to perform.
The values assigned to instructions are mostly arbitrary. For example, a processor designer might decide that 0x02 means “move,” while another design could use 0xEF for the same operation. The CPU’s control circuitry is built to recognize the chosen bit pattern and activate the appropriate circuits. Once that instruction set is defined, assemblers and compilers translate human-readable code into those machine instructions.
So there wasn’t one universal rulebook assigning meanings to every number. The designers defined an instruction set and constructed the circuitry to behave accordingly. Standards became important later so different machines and programs could interoperate.