What is a Motherboard and What Does it Do?

Electronic devices are comprised of various hardware, firmware, and software systems. A phone, for example, has Wi-Fi antennas, cellular antennas, cameras, memory/storage, LCD or OLED touch screen, and biometric security devices like face ID and fingerprint readers that all need to work together to communicate effectively with each other. Most of the time, these embedded systems are made by various manufacturers and run different protocols from one another. How do they all connect, you might ask? The answer is through a motherboard.

What is a Motherboard?

A motherboard is found at the heart of all electronic devices on the market and is often called just that; the heart of a device/system. A quick search in the dictionary will tell you that a motherboard is “a rigid, slotted board upon which other boards that contain the basic circuitry of a computer or of a computer component can be mounted.” – Dictionary.com. The motherboard is what connects all embedded systems within a device together. It allows the different devices to be connected through the complex wiring and circuitry on the board.

A few different names are used in the tech sphere to refer to a motherboard, including, mb, mainboard, mboard, backplane board, mobd, mobo, main circuit board, base board, planer board, system board, or a logic board. A motherboard can be found in almost all electronic devices. They vary in size and capability depending on the application, but at their base level, they serve the same purpose; they connect devices to make a single, unified machine.


Photo by: Andrew Matveev

The First Motherboard

The motherboard was first introduced to the world by IBM in 1981 and was called the “planar.” It housed a CPU and RAM and served a very basic purpose. The board had chips wired together and ports for a keyboard, mouse, and cassette tapes. The original PC, built on this motherboard, set the standard for many computer hardware specifications in computers for years to come.

First Motherboard

Photo by: Sutori

How Does a Motherboard Work?

As we established above, motherboards are the heart of most modern-day devices because they connect all system components and allow them to talk to each other. A motherboard, however, does not have any computing power. The board is simply a building block for a device, but the device requires external logic from a CPU (Central Processing Unit) to send and receive messages to the other embedded systems on the board. The CPU is responsible for running the system as a whole and can be thought of as the brain of a device because it is the one deciding what can and cannot be done. The motherboard allows the CPU to communicate with the other systems. Comprised of a sandwich of fiberglass and copper wiring, the motherboard provides an electrical highway for signals to travel.

Motherboard Components and Their Functions.

Not all motherboards are built to do the same thing. Depending on the board's application, there may be more or less connection options compared to another board for another application. There are some components, however, that are generally found on most, if not all, motherboards.

CPU Slot

The CPU executes instructions that make up a program. Also known as a central processor unit or the main processor, the CPU is the brain of the computer. The CPU executes instructions specified by desktop programs.

CPU Slot on Motherboard

RAM Slots

Random-Access Memory (RAM) stores programs and data currently used by the CPU. RAM is computer memory that can be read and written. A RAM storage device allows the CPU access to extremely fast memory for current tasks. The storage can be written to and read from nearly the same time no matter where the data is in the memory, making it excellent for fast and snappy commands.

RAM Slots on Motherboard

General I/O Ports

On each circuit board, there are various input and output ports. The connections generally include multiple USB connections, a few display connections (HDMI, USB-C, Thunderbolt, DisplayPort), and perhaps some networking I/O like an ethernet connection. These ports allow external devices to interface with the system as a whole.

General I:O Ports on Motherboard

Power Supply Plug-In

The power supply provides the computer with the necessary power to operate. Power supplies range in voltages depending on how power-hungry the device is. The power supply for gaming computers, servers, and power-demanding applications is significantly larger than that of a phone or smartwatch.

Power Supply Plug In on Motherboard

CMOS Battery

The CMOS battery, also called memory battery, clock battery, or real-time clock (RTC), is generally a CR2032 lithium coin cell. The purpose of the battery is to store the board's BIOS (Basic Input/Output System) settings when the motherboard is entirely powered off. This way, the BIOS is not lost when no power is supplied to the board.

CMOS Battery on Motherboard


Development Tools for Motherboards

Motherboards allow various protocols to run in a system at the same time. Protocols from DDR3 and DDR4 for connected hard drives and DDR5 for graphics, PCIe (NVM Express) for Flash storage, and SPI and I2C for the low-level board and system operations, these protocols run on the same motherboard with seamless integration. During motherboard development, these protocols often require a combination of debugging software and hardware tools to ensure they are running as intended.

From the Aardvark I2C/SPI Host Adapter, to the Cheetah SPI Host Adapter, to the Promira Serial Platform, to the Beagle I2C/SPI Protocol Analyzer, Total Phase offers a range of tools and solutions to fit almost any SPI and I2C development applications. With programming speeds ranging from 4 MHz to 80 MHz as an SPI master and from 4 MHz to 20 MHz as a slave, and from 800 kHz to 3.4 kHz as an I2C master and slave, these adapters make for an excellent choice for developing I2C- and SPI-based embedded systems. On the other hand, the Beagle I2C/SPI Protocol Analyzer allows users to non-intrusively monitor both the I2C and SPI bus in real-time, allowing for greater insight into the traffic occurring on the bus.

These tools allow engineers to create and debug their solutions so that their products work seamlessly in their intended applications.


Motherboards are at the heart of almost all electronic devices on the market. Motherboards are everywhere, from the phone you use daily, the microwave in your kitchen, the car you drive, to the computer you use at home and work. They allow various embedded systems from manufacturers that serve different purposes to communicate and work effectively together to create a unified, cohesive system. Without the modern-day motherboard, we would not have the technology that we get to enjoy on a day-to-day basis.