---
title: "Criteria for selecting a processor"
subject: "Embedded System"
chapter: 2
key: "semester_6/embedded_system:processor-selection-criteria"
source: https://www.bctengineer.com/q/semester_6/embedded_system/processor-selection-criteria
site: BCT Engineering
---

# Criteria for selecting a processor

Embedded System · Chapter 2: Hardware Design Issues

- Asked in: 2072 Asoj, 4 marks; 2076 Baisakh, 4 marks (asked 2 times)
- Video: [1 1 1 Processor selection criteria](https://www.youtube.com/watch?v=0KTd8cIpiPU) — MSBTE Electronics and more
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/embedded_system/processor-selection-criteria
- Whole chapter: https://www.bctengineer.com/md/semester_6/embedded_system/chapter-2

## Question

Briefly explain the criteria for selecting a processor (microprocessor) in an embedded system.

## Short answer

Key criteria include performance (speed, word length), power consumption, cost, on-chip memory and peripherals, interrupt handling, instruction set suitability, development tools, and availability. Real-time constraints and time-to-market also influence the choice.

## Answer

Choosing the processor is a key design decision. The criteria are:

1. **Performance (speed):** clock rate, MIPS, instruction cycle time and word length must meet the required response time or throughput.
2. **Word length (data width):** 8, 16 or 32 bits, depending on the data precision and the amount of computation.
3. **Memory:** amount of on-chip RAM and ROM/flash and the addressable space; external memory interface needed or not.
4. **Power consumption:** low-power modes are vital for battery devices.
5. **Cost:** unit price and total system cost, including peripheral chips.
6. **On-chip peripherals and I/O:** timers, ADC/DAC, serial ports (UART, SPI, I2C), PWM, number of I/O pins; fewer external chips are needed.
7. **Interrupt handling:** number of interrupt sources and latency for real-time response.
8. **Instruction set and architecture:** suitability for the task (e.g. MAC for DSP, bit instructions for control); RISC or CISC.
9. **Development tools and support:** compilers, debuggers, emulators, RTOS availability, programmer's familiarity, documentation.
10. **Availability and reliability:** supply, vendor reputation, package size and operating temperature range.
11. **Time-to-market / reuse:** existing software/IP and legacy code.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which factors show a processor's performance?
   A. Clock rate, MIPS, instruction cycle time and word length
   B. Package colour
   C. Vendor name
   D. Price
   Answer: A. They must meet required response time or throughput. (Key point: Performance)

2. Why do on-chip peripherals (timers, ADC, UART) matter?
   A. They increase cost
   B. Fewer external chips are needed
   C. They remove memory
   D. They slow interrupts
   Answer: B. Integrated peripherals reduce chip count, cost and size. (Key point: On-chip peripherals)

3. Why is interrupt handling a criterion?
   A. It decides colour
   B. It sets package size
   C. Number of sources and latency decide real-time response
   D. It is irrelevant
   Answer: C. Real-time response depends on interrupt latency and number of sources. (Key point: Interrupts)

4. Which is development tools and support criterion?
   A. Logo
   B. Case colour
   C. Battery colour
   D. Compilers, debuggers, emulators, RTOS availability
   Answer: D. Tool support and familiarity affect time-to-market. (Key point: Development support)

## Related in Embedded System

- [Processor is heart of embedded system](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Aprocessor-heart-structural-units) — Embedded System, chapter 2
- [Define embedded system and its applications](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Adefine-embedded-system-applications) — Embedded System, chapter 1, asked 4×
- [Design metrics of embedded system](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Adesign-metrics-embedded) — Embedded System, chapter 1, asked 3×
- [Define embedded system and its characteristics](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Adefine-embedded-system-characteristics) — Embedded System, chapter 1, asked 2×
- [Digital camera as embedded system](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Adigital-camera-embedded-example) — Embedded System, chapter 1, asked 2×
- [Embedded system types and definition difficulty](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Aembedded-types-hard-to-define) — Embedded System, chapter 1

## Related in other subjects

- [Selecting a processor or microcontroller](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aprocessor-selection) — Instrumentation II, chapter 1, asked 4×
- [Criteria for selecting a water source](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Aselection-criteria-water-source) — Water Supply Engineering, chapter 2, asked 5×
- [Criteria for selecting a suitable scale](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Acriteria-selecting-scale) — Surveying I, chapter 1, asked 2×
- [Microprocessor based system and bus organization](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3Amp-based-system-bus-organization) — Microprocessor, chapter 1, asked 5×