Definition
The part of a digital computer that carries out the instructions of a program. It performs the arithmetic and logic operations, controls the flow of data between memory and other components, and coordinates the activity of the rest of the system.
Plain English
The 'thinking' part of a computer. It does the calculations and tells the rest of the system what to do.
Context Anchor
Seen in descriptions of avionics, engine monitors, flight displays, navigation equipment, and maintenance troubleshooting for computer-based aircraft systems.
Derivation
From Latin 'centralis' (in the middle, the main one), 'processus' (a going forward, a working through), and 'unit' (a single thing). Together it means 'the main working part.' That captures the idea well -- it's the one piece of the computer that actually does the work of running the program.
Why Pilots Care
Modern aircraft depend on reliable CPUs in glass cockpits and flight management systems to display accurate navigation and engine data; a CPU fault can remove critical information from the pilot's view.
Analogy
A central processing unit is like the person in an office who reads the instructions, does the calculations, and tells everyone else what task to perform next.
Intuition Check
Do not think of the central processing unit as the whole computer, the screen, or the entire aircraft system. It is the main internal part that carries out instructions and controls data flow.
Example Sentence 1
The GPS unit froze on the ramp, so we cycled the power to let the central processing unit restart.
Example Sentence 2
During troubleshooting the technician isolated the fault to the central processing unit rather than a sensor.