Back in college, one of my classes dealt with circuit design. The hands-on lab was building

a robot from scratch. Well, mostly from scratch. The first step was to design the printed circuit

board, PCB, and build it. We were given a plain 3x5 inch or 8x13 centimeter blank

link PCB. The board starts out as a flat piece of fiberglass with a thin layer of copper on top.

To create our circuit, we transferred our design onto that copper layer with a protective film

that covered the parts we wanted to keep. Then the board went into an acid bath which ate away

all the uncovered copper, leaving behind just the traces that made up our circuit. This process is

called etching and when it was done, we cleaned the board, drilled any holes we needed, and soldered

all the components on. The capacitors, resistors, chips, and everything else. We then built the rest

of our robot and used our PCB to control it. This was a pretty simple board I made. It only handled

a few basic functions and had just a handful of traces, nothing fancy. But what's cool about it

is that this same process is how real motherboards are made, just on a much larger scale. The

difference is that they use much smaller, more precise components, and the soldering is done

with incredible accuracy by machines. Not by some college kid with an $8 soldering iron.

The part that is essential for all your computer components to communicate,

on this episode of in the shell. The wrong thing to do is just go out and buy a computer and then

learn about it. You'll learn, but you'll learn a lot of things that maybe you didn't want to learn.

A computer that you buy today will likely be obsolete six months from now and there's not a

dang thing that you can do about it. A motherboard is the main circuit board that holds and connects

all the core components of a computer. Think of it as the PC's central backbone or nervous system.

It's the large flat board you see when you open a desktop computer with the CPU, memory sticks,

and other cards or components plugged into it. In laptops and smartphones, it's usually a smaller,

densely packed board, often called a logic board, which is Apple's term, or just system board,

but it serves the same purpose, tying all the pieces together so they can communicate and work

as one. And why the name motherboard? The motherboard is the mother to all smaller boards.

You can plug in daughter boards, like expansion cards, into it to add functionality, hence the naming.

Early computers had simpler main boards that weren't easily extensible, but once engineers enabled

plugging in add-on cards, the term motherboard stuck. So what's actually on a motherboard and how does it

work? A motherboard is a printed circuit board, PCB, a hard, thin board made of non-conductive material,

usually fiberglass or plastic, with layers of copper pathways printed onto it. Those copper pathways,

called traces, are like tiny highways for electrical signals. They link all the different sockets and

components on the board, allowing data and power to flow between the CPU, memory, storage, and

peripheral devices. Importantly, the motherboard doesn't compute or store data the way a CPU or

hard drive does. Instead, it distributes power and data between those components.

When you plug in the computer's power supply to the motherboard, that power is routed through voltage

regulators on the board to the CPU and other components. The motherboard provides the physical

connections and communication channels so that your CPU can talk to your RAM through a memory bus built into

the board or send data to your storage drives via SATA or NVMe connections. Every major component either

plugs into the motherboard or is built onto it. For example, the CPU sits in a socket on the

the board, memory modules snap into slots, and your SSD or hard drive connects via a cable or

M.2 slot on the board. Even external devices, like a keyboard, mouse, or monitor, ultimately connect

into the motherboard's ports. Without the motherboard acting as a hub, all those parts

would just be isolated bits. There'd be no way for the CPU to use the RAM or communicate with

storage and input and output devices. Most motherboards also include a number of controller

chips, collectively called the chipset. The chipset is like the traffic director on the board.

It manages communication between the CPU, memory, and peripherals. In older PCs, you'll find two main

chips, nicknamed Northbridge and Southbridge, one focused on fast connection.

ones like the CPU memory and graphics, the other on slower I.O. like disk drives. Modern

designs have consolidated these. Today's CPUs have the memory and often graphics controllers

built right into the processors, so the traditional north bridge is gone. The motherboard usually

has a single chipset chip, which on Intel systems is often called a PCH, which stands

for Platform Controller Hub, which handles things like USB ports, SATA drives, networking, and

other I.O. This evolution means data can move more directly and faster in many cases, but

the principle is the same. One crucial component on the motherboard is the BIOS or UEFI chip,

a small, non-volatile memory chip, that contains the firmware, and a small, non-volatile memory

which is low-level software, that kicks everything off when you power up the PC.

When you turn on your computer, the code in the BIOS runs first. It checks what hardware is present,

doing a power-on self-test, makes sure things are in order, and then boots up the operating

system from your drive. Without this firmware, your CPU wouldn't know how to get started.

The BIOS settings interface, which you might have seen, where you can change boot order or enable and

disable features, is stored on this chip on the motherboard. So in a sense, the motherboard is

not just some dumb backplane. It also houses this critical firmware and some specialty controllers.

The concept of the motherboard evolved over time as computers shrank from room-sized monsters

to the PCs we know of.

In the early days of computers, the 1940s to 1960s, there wasn't a single board that held the whole computer together.

This started to change once the microprocessor was invented.

In the mid-1970s, computers like the MITS Altair used a microprocessor and had a bunch of boards plugged into the backplane.

But soon, engineers realized you could put the CPU and some support circuitry on one board, and then have expansion slots for additional capabilities.

Throughout the late 80s and 90s, motherboards kept integrating more functions.

Initially, to get sound or networking, you'd install a separate sound card or network card.

But manufacturers realized it was cheaper, and users liked it, if more features were built on board.

By the end of the 1990s, it was common for motherboards to include things like audio codecs, basic 3D video, modem or network adapters, and I.O. ports without needing separate cards.

This evolution also went hand-in-hand with smaller computers.

Laptops in the 1990s pushed integration further.

You can't have room for many plug-in cards in a laptop, so the motherboard or logic board in a laptop contains nearly everything.

Today, devices like smartphones and tablets take this to the extreme.

Their motherboards are highly integrated.

Every essential component is on one tiny board.

This makes for sleek, compact devices, though at the cost of upgradability.

In the desktop world...

we still have the modular motherboards for flexibility and power.

Whether it's a gigantic backplane in a 1960s mainframe,

or a colorful RGB lit gaming motherboard in 2025,

the fundamental job is the same.

Provide a hub for all components to communicate and share power.

In the Shell is written, researched, and recorded by me,

the PCB podcaster.

If you are listening in an app that lets you rate shows,

please take a minute to rate this one.

I would truly appreciate it.

And remember, call your motherboard.

She worries when you don't stay connected.

That's it. Take care, and I'll see you next time.

You