--- title: "Prototyping model of software" subject: "Instrumentation II" chapter: 9 key: "semester_5/instrumentation_ii:prototype-model" source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/prototype-model site: BCT Engineering --- # Prototyping model of software Instrumentation II · Chapter 9: Software For Instrumentation And Control Applications - Asked in: 2074 Chaitra, 3 marks; 2078 Bhadra, 4 marks; 2068 Baisakh (old course), 8 marks (asked 3 times) - Answer checked by Claude Sonnet 5.5 on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/prototype-model - Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-9 ## Question Explain the Prototyping Model of software development with its components, merits and demerits. ## Short answer The prototyping model builds an early sample for user evaluation, refining requirements through feedback cycles. It reduces misunderstanding and risk, but may lead to scope creep, poor documentation, and customers mistaking prototype for final product. ## Answer #### Prototyping model The **prototyping model** builds a working sample (prototype) of the system early, with limited functions, so that users can see and evaluate it. Their feedback is used to refine the requirements, and the prototype is revised until the user is satisfied; then the final system is developed (or the prototype evolved into it). It is useful when the requirements are unclear or unstable (e.g. new user interface or an instrumentation display). ```text Requirements gathering | Quick design | Build prototype <----------+ | | Customer evaluation --(refine) | (accepted) Final design -> Implement -> Test -> Maintain ``` #### Components (phases) 1. **Requirements gathering:** initial, rough requirements from the users. 2. **Quick design:** a simple design of the visible parts (inputs, outputs, screens). 3. **Prototype building:** quick implementation of a partial system (throw-away or evolutionary). 4. **User evaluation:** customer tests and gives feedback. 5. **Refinement:** the requirements and prototype are revised; the cycle repeats. 6. **Final product:** engineering of the full system, testing, deployment and maintenance. #### Merits - Misunderstandings in requirements are found early, so the final system suits users better. - Users participate actively; higher satisfaction. - Reduces the risk and cost of late changes; missing functionality is detected early. - Useful for unclear requirements and for demonstrating feasibility. #### Demerits - Customers may take the prototype as the final product and expect fast delivery; the quick-and-dirty prototype code may be kept, with a poor structure. - Time and cost may increase through repeated cycles; scope creep. - Documentation is often poor; hard to plan and estimate. - Developers may make poor design choices to build the prototype fast. - Not suitable for large, well-defined, safety-critical systems. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. When is the prototyping model most useful? A. Requirements are clear and stable B. Requirements are unclear or unstable C. No user is available D. Large safety-critical systems Answer: B. A working sample lets users clarify requirements. (Key point: Purpose of prototyping) 2. What happens after customer evaluation of a prototype? A. Requirements and prototype are refined and the cycle repeats until accepted B. Project is cancelled C. Maintenance starts D. Testing is skipped Answer: A. Feedback drives refinement until the user is satisfied, then the final system is built. (Key point: Cycle) 3. Which is a merit? A. Poor documentation B. Misunderstandings in requirements are found early C. Increased scope creep D. Poor code structure Answer: B. Early user involvement reveals requirement errors. (Key point: Merit) 4. Which is a demerit? A. Customers may treat the prototype as the final product and quick-and-dirty code may be kept B. Users cannot participate C. No feedback D. Late discovery of missing functions Answer: A. Prototype code with poor structure may remain, with unrealistic expectations of delivery. (Key point: Demerit) ## Related in Instrumentation II - [Spiral model of software development](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aspiral-model) — Instrumentation II, chapter 9, asked 3× - [Software reliability; waterfall vs prototyping; embedded software](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Asw-reliability-models-embedded) — Instrumentation II, chapter 9 - [Software process models and effort estimation](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Asw-process-models) — Instrumentation II, chapter 9, asked 2× - [Compare software models; propose a fourth model](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Asw-models-compare-fourth) — Instrumentation II, chapter 9 - [Shortcomings of software development models](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Asw-model-shortcomings) — Instrumentation II, chapter 9 - [Embedded real-time software; model for project](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aembedded-rt-software-model) — Instrumentation II, chapter 9 ## Related in other subjects - [Software runaways; waterfall and prototyping inside spiral](https://www.bctengineer.com/question.md?key=semester_5%2Fsoftware_engineering%3Asoftware-runaways-spiral) — Software Engineering, chapter 1 - [Cofferdam types, uses, merits and demerits](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Acofferdam-types-merits) — Foundation Engineering, chapter 5, asked 7× - [Incineration: merits and demerits](https://www.bctengineer.com/question.md?key=semester_6%2Fsanitary_engineering%3Asolid-waste-incineration) — Sanitary Engineering, chapter 10, asked 7× - [Merits and demerits of river and ridge routes](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ariver-ridge) — Transportation Engineering I, chapter 5, asked 7×