Definition
In computing and avionics, any device connected to a central processor that supports its operation but is not part of the processor itself. Peripheral equipment includes input devices (such as keyboards or sensors), output devices (such as displays or printers), and storage devices (such as disk drives or memory modules).
Plain English
The supporting devices that connect to a computer or processing unit. The processor does the thinking; the peripheral equipment lets it take in information, send it out, or store it.
Context Anchor
Seen in aircraft maintenance, avionics installation, equipment descriptions, and troubleshooting notes.
Derivation
From the Greek peripherein, meaning 'to carry around.' A peripheral sits around the central unit — connected to it, but on the outside. That image matches the technical meaning: the processor is at the center, and these devices are arranged around it.
Why Pilots Care
When troubleshooting an avionics issue, the fault may not be in the processor itself but in a peripheral — a failed sensor, a frozen display, or a faulty input device. Knowing the distinction helps a pilot describe the problem accurately to maintenance.
Analogy
A monitor connected to a computer is like peripheral equipment: it is not the computer itself, but it helps you use the computer.
Intuition Check
Do not read “peripheral” as “unimportant.” In this context, peripheral equipment may be separate from the main unit, but it can still be needed for the system to work properly.
Example Sentence 1
The flight management computer was working correctly, but a peripheral equipment failure in the display unit blanked the screen.
Example Sentence 2
New displays were added as peripheral equipment to the existing navigation system.