What defines a system as ‘real-time’?
It has a deterministic response to a given event
What is an example of a hard real-time system out of the following: cruise control, a pacemaker, a video playback system, and a basic calculator?
Pacemaker
What is the main advantage of using hardware-based real-time systems?
Parallel and instantaneous operations.
What is the primary downside of using custom ASICs in real-time systems?
Inflexibility and high cost.
What is the key feature of RTOS-based firmware?
It introduces a scheduling kernel.
Which of the following is true about bare-metal firmware:
a) it relies on pre-existing schedulers
b) it always uses vendor-supplied libraries
c) it offers high control over hardware
d) it cannot handle interrupts
c) It offers high control over hardware
What distinguishes a soft real-time system from a hard real-time system?
Deadlines are less critical in soft real-time systems.
Why are RTOSes preferred for constrained devices?
They provide a compact real-time kernel.
What is a firm real-time system’s behaviour when it misses occasional deadlines?
It may degrade performance without catastrophic failure.
In a real-time system, which condition most precisely defines system failure?
The system produces a correct result after its deadline (i.e. the deadline was missed).
Which pair of factors best explains why real-time requirements vary widely across systems?
Execution speed and severity of missed deadlines.
Which statement best characterizes deadline misses in real-time systems?
a) All deadline misses lead to catastrophic system failure
b) Deadline misses are acceptable if results remain correct
c) Deadline misses may be acceptable or catastrophic depending on the system
d) Deadline misses are only problematic in hardware-based systems
c) Deadline misses may be acceptable of catasrophic depending on the system.
In the context of real-time systems, what does bandwidth refer to?
The system’s ability to respond to events and signals.
What is the primary risk of insufficient system bandwidth in a real-time system?
Loss of signal integrity and late responses.
What hardware characteristic most directly limits the number of instructions executed per unit time?
Clock frequency and cycles per instruction.
What factors is least directly responsible for software performance in a real-time system?
a) Algorithm complexity
b) Operating system behavior
c) Multitasking and timing mechanisms
d) ADC sampling voltage range
d) ADC sampling voltage range (it may affect accuracy, but not software timing performance)
Why is a real-time system design considered challenging?
It requires a deep understanding of both hardware and software.
Why is real-time system design describe as both a science and an art?
Science involves analysis and timing calculations, art involves trade-offs.
In the soldering iron example, which component combination directly supports maintaining a constant tip temperature?
Temperature sensor, ADC, MCU, and heater.
Why do real-time constraints vary widely across different systems?
Because timing speed and consequence severity differ.
Why is the MCU-controlled soldering iron shown in the slides considered a closed-loop control system?
Because the measured tip temperature is fed back to the MCU to adjust the heating power.
Why does keeping a real-time system simple help guarantee real-time behaviour?
Because simpler systems make timing behviour more predictable.
According to the toaster example, what best illustrates the KISS principle in system
design?
a) Adding a display improves usability without affecting reliability
b) Including extra features makes the system more versatile
c) A simple design is acceptable only for non-real-time systems
d) Limiting functionality to the core task improves reliability
d) Limiting functionality to the core task improves reliability.
What distinguishes a chip-level subsystem from a board-level subsystem?
It is contained within a single physical device.
