L1 - Introduction Flashcards
Soft Real Time Systems have ____________ but missed deadlines are __________. Name an example.
Soft Real Time Systems have limited time for completion but missed deadlines are acceptable (e.g. videos).
How is a time triggered application defined?
The time cycle of a time triggered application is determined at compile time which makes them predictable (deterministic behavior). A precise synchronization is essential.
What are the three mapping policies for the cache?
direct, set associative, fully associative
What is Coherence?
data uniformity in shared resources. Means: single writer, multiple reader.
How is a event driven application defined?
In event driven systems; executions are triggered by the occurrence of events for which guaranteed response times are essential.
A Real Time System (RTS) is often …
A Real Time System (RTS) is often distributed and need to be fault tolerant.
Hard Real Time Systems have ____________ and missed deadlines are __________. Name an example.
Soft Real Time Systems have limited time for completion and missed deadlines are not acceptable and can lead to severe consequences (e.g. rocket control).
Instants
Instants are points in time, infinite and a ordered set.
What time requirements should a RTS meet?
- temporal accuracy
- guaranteed response times
- synchronization of events
What are Embedded Systems?
ES are computer systems within a larger mechanical or electrical system. They do often have real-time computing constraints, limited processing power and not much storage capacity.
A Real Time Computer System is a computer system in which the accuracy of the system depends not only on the ____________________ but also by the ___________________ in which the result is produced.
logical result of the calculation & physical moment
What does Design specify and in what elements can it be divided?
Design specifies which services the system does provide.
It consists out of…
- Implementation
- Execution
- Hardware/Software.
What does Analysis describe?
Analysis explains why the system does what it does.
Name three characteristics of a stack.
- stack is a memory segment in RAM operating on the LIFO principle
- Stack pointer (register) contains the memory address of topmost value
- in concurrent systems, each thread has its own stack
- very fast memory allocation
Which time problems can occur in a RTS?
- Processing (Discretization, Drift,Synchronization)
- Execution (Determinism, Parallelism, Process Synchronization)
