Definition
A number expressed using eight binary digits (bits), where each bit is either 0 or 1. An 8-bit binary number can represent 256 different values (from 0 to 255 in unsigned form). This grouping of eight bits is also called a byte.
Plain English
A number written using only zeros and ones, made up of eight digits in a row. With eight digits, you can count from 0 up to 255.
Context Anchor
Seen in aircraft electronic equipment discussions, especially when maintenance material describes computer data, stored values, or signals between electronic units.
Derivation
Binary' comes from the Latin 'binarius', meaning 'consisting of two', because each digit has only two possible values: 0 or 1. 'Bit' is short for 'binary digit'. Eight of these together form a byte, which became the standard unit because it can represent any single character of text or a useful range of numbers.
Why Pilots Care
Modern avionics, transponders, and digital flight instruments all process information in bits and bytes. Knowing what an 8-bit number is helps technicians understand data formats, fault codes, and how digital systems store values.
Analogy
Think of eight small switches in a row. Each switch can be off or on. With eight switches, there are 256 different on-off patterns.
Intuition Check
Do not read “8-bit” as eight ordinary decimal digits. Here, it means eight binary places, and each place can only be 0 or 1.
Example Sentence 1
The transponder code was stored internally as an 8-bit binary number, allowing values from 0 to 255.
Example Sentence 2
Maintenance software reads the 8-bit binary number stored in memory to check system status.