5 Questions
Which type of time deals with a quantitative notion of time measured using a physical clock?
Real time
What kind of time is expressed using terms like 'before,' 'after,' 'sometimes,' and 'eventually'?
Logical time
In a real-time system, what must occur during the evolution of external events?
Reactions
How is system time measured in relation to the external environment in a real-time system?
Same time scale
When is a system considered a real-time system?
$100<200$ mSec response time
Study Notes
Real Time and Logical Time
- Real Time is a quantitative notion of time measured using a physical clock.
- Example of Real Time: after a certain event occurs (temperature exceeds 250°C), the corresponding action (coolant shower) must complete within 100 mSec.
- Real Time indicates reaction to external events must occur during their evolution.
System Time
- System Time (internal time) has to be measured with the same time scale as the controlled environment (external environment).
Real-Time System
- A system can be called a real-time system when quantitative time is used to describe the behavior of the system.
Logical Time
- Logical Time (aka Virtual Time) deals with a qualitative notion of time.
- Example of Logical Time: expressed as ‘before’, ‘after’, ‘sometimes’, ‘eventually’, etc.
Learn about the concepts of real time and logical time in the context of system time measurement. Understand the difference between quantitative and qualitative notions of time and how they apply to system behavior and event responses.
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