Computer Electronics

Underneath every computer is the same handful of building blocks: a processor that executes instructions, memory that holds data and programs, buses that move information between them, and a clock that keeps everything in step. This covers the hardware architecture — the counterpart to the Computer Applications page, which covers ports, networking, and software.

The CPU (Central Processing Unit) — the microprocessor when built on one chip — is the brain that fetches, decodes, and executes instructions. Inside it are three core sections: the ALU (Arithmetic Logic Unit) that does the math and logic, the control unit that sequences operations, and a set of registers — tiny fast storage cells for the data being worked on right now.

The CPU runs a relentless fetch–decode–execute cycle: fetch the next instruction from memory, decode what it means, execute it, repeat — billions of times a second.

The CPU connects to memory and I/O through the system bus — a set of parallel lines, traditionally grouped into three:

Everything in a synchronous computer marches to a clock — a steady square-wave from a crystal oscillatoriA quartz crystal vibrates at a precise frequency (the piezoelectric effect), giving the clock its stability. Clock speed is measured in Hz — MHz and GHz for modern CPUs. that synchronizes every operation. Each tick steps the processor through its cycle. Clock speed (in MHz/GHz) is roughly how many cycles run per second — higher generally means more instructions per second, though architecture matters too.

Computers represent everything — numbers, characters, instructions — as combinations of 0s and 1s (binary). A single 0/1 is a bit; 8 bits make a byte, which can represent 2⁸ = 256 distinct values. Characters are encoded in schemes like ASCII.