- 2075 Asoj · 2+3+3 marks
Software reliability; waterfall vs prototyping; embedded software
Short answer
Software reliability is the probability of failure-free operation for a specified time and environment. Waterfall follows sequential phases with fixed requirements, while prototyping refines through customer feedback and early versions. Embedded software is dedicated firmware in a device with limited resources; real-time software must meet strict timing deadlines, often using interrupts and a RTOS.
What is software reliability? Compare waterfall and prototyping model. Describe Embedded and Real Time Software.
Software reliability
Software reliability is the probability that software performs its required function without failure for a specified time in a specified environment. It is improved by testing and bug removal, and is measured by failure rate, MTBF and defect density. Unlike hardware, software does not wear out; failures are due to design faults.
Waterfall vs prototyping
| Point | Waterfall | Prototyping |
|---|---|---|
| Process | Sequential phases | Build, evaluate, refine prototype |
| Requirements | Fixed at start | Evolve with feedback |
| Customer involvement | Mostly at start and end | Throughout |
| Working version | Late | Early |
| Risk | High if requirements are wrong | Lower |
| Documentation | Good | Often poor |
| Cost of change | High | Lower in early stage |
| Best for | Clear, stable requirements | Unclear requirements, user interfaces |
Embedded and real-time software
Embedded software is a program stored in the memory of a microcontroller/processor built into a device for a dedicated function, interacting directly with the hardware, and with limited resources. Real-time software must respond to events and produce results within strict time deadlines (hard or soft), using interrupts, timers and often a real-time operating system. Most instruments are both: embedded real-time software.
✓ Answer checked by Claude Sonnet 5.5
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