# Chip, module, SoM, dev board, SBC

The same processor is sold as a bare chip, a module or a ready-made board. Their prices are not comparable, and mixing them up is a common mistake.

Page: https://dharanova.com/learn/chip-som-board · Track: Think · Level: Foundation · Facts last checked 7 October 2026

Read first: [Microcontroller or microprocessor?](https://dharanova.com/learn/mcu-vs-mpu.md)

Diagram: Three columns. Bare application processor: the silicon alone; you still add external DRAM, boot storage, a PMIC or regulators, a crystal, a reset circuit, a multi-layer PCB and DDR routing with length-matched traces. System-on-module: the chip plus DRAM, storage and power management; you add your own carrier board and what it carries, with no DDR routing of your own. Dev board or SBC: nothing to design; it is complete and boots on a desk. Below: a pre-certified radio module (wireless chip plus RF circuitry) whose approval a product can reuse only under its conditions.

## Key points

1. A bare chip is the silicon alone. A system-on-module (SoM) adds DRAM, storage and power management on a small board that plugs or solders onto your carrier board. A development board or single-board computer (SBC) is complete and boots on a desk. [1]
2. An application processor cannot run alone: a product also needs external DRAM, boot storage, a PMIC or regulators, a crystal, a reset circuit and a multi-layer PCB (one vendor's guide recommends at least eight layers for its part). [2][1]
3. Routing external DDR memory demands controlled-impedance, length-matched traces on a multi-layer board. Vendors publish dedicated DDR layout guidelines, and buying a SoM is one way to avoid doing this routing yourself. [2]
4. A pre-certified radio module packages a wireless chip with its RF circuitry. In the US and some other markets, a product can reuse the module's radio approval, but only with the antennas and conditions in that approval, and only where the module is approved. The product still needs its own tests, such as emissions. [3][4]

## Common mistakes

- Comparing a bare chip's price with a dev board's price. They are different products.

## Where to go next

- [Anatomy of an application-processor system](https://dharanova.com/learn/anatomy-of-an-mpu-system.md): What sits around the processor on a Linux board, and how it starts up, from power-on to a login prompt.
- [Choosing a microcontroller or processor](https://dharanova.com/learn/choosing-a-processor.md): Answer six questions to find the kind of chip that fits your project, from small microcontrollers to Linux-class processors. You get a class, not a brand.

## Sources

1. [Raspberry Pi Compute Module 5 datasheet](https://datasheets.raspberrypi.com/cm5/cm5-datasheet.pdf), Raspberry Pi
2. [i.MX 8M Mini Hardware Developer's Guide (IMX8MMHDG) Rev. 4.1](https://community.nxp.com/pwmxy87654/attachments/pwmxy87654/imx-processors/218788/1/IMX8MMHDG-NEW.pdf), NXP
3. [KDB 996369 D04 Modular Transmitter Integration Guide: Guidance for Host Product Manufacturers (public draft review copy, April 2020)](https://apps.fcc.gov/eas/comments/GetPublishedDocument.html?id=451&tn=825049), US FCC Office of Engineering and Technology
4. [Espressif certificates](https://www.espressif.com/en/support/documents/certificates), Espressif