from
Jargon File (4.4.4, 14 Aug 2003)
real time
1. [techspeak] adj. Describes an application which requires a program
to respond to stimuli within some small upper limit of response time
(typically milli- or microseconds). Process control at a chemical
plant is the {canonical} example. Such applications often require
special operating systems (because everything else must take a back
seat to response time) and speed-tuned hardware.
2. adv. In jargon, refers to doing something while people are watching
or waiting. "I asked her how to find the calling procedure's program
counter on the stack and she came up with an algorithm in real time."