Questions and Answers

Q1 Which of the following is a real time embedded system? Justify your answer
(a) Ceiling Fan
(b) Microwave Oven
(c) Television Set
(d) Desktop Key Board
(e) Digital Camera
Ans:
(b) and (e) are embedded systems
(
(a) Ceiling Fans: These are not programmable.
(b) & (e) obey all definitions of Embedded Systems such as
(i) Working in Real Time (ii) Programmable (iii) A number of systems coexist on a single platform to discharge one function(single functioned)
(c) Television Set: Only a small part of it is programmable. It can work without being programmable. It is not tightly constrained.
(d) Desktop Keyboard: Though it has a processor normally it is not programmable


Q.2 Write five advantages and five disadvantages of embodiment.
Ans:
Five advantages:
1. Smaller Size
2. Smaller Weight
3. Lower Power Consumption
4. Lower Electromagnetic Interference
5. Lower Price
Five disadvantages
1. Lower Mean Time Between Failure
2. Repair and Maintenance is not possible
3. Faster Obsolesce
4. Unmanageable Heat Loss
5. Difficult to Design

Q3. What do you mean by Reactive in Real Time. Cite an example.
Ans:
Many embedded systems must continually react to changes in the system’s environment and must compute certain results in real time without delay. For example, a car’s cruise controller continually monitors and reacts to speed and brake sensors. It must compute acceleration or deceleration amounts repeatedly within a limited time; a delayed computation could result in a failure to maintain control of the car. In contrast a desktop computer system typically focuses on computations, with relatively infrequent (from the computer’s perspective) reactions to input devices. In addition, a delay in those computations, while perhaps inconvenient to the computer user, typically does not result in a system failure.