Motherboard: How Do Parts Fit Together?

One of the most complex-looking parts of a computer’s internals is its “motherboard”.

Ironically, while motherboards often look intimidating, they’re one of the least complex parts of a computer. In effect, they’re simply a “printed circuit board” (PCB) with “ports” for a CPU, onboard memory (as RAM), an input (typically for at least a keyboard or other computer data), and an output (typically via a screen). In most typical computers, there are other built-in features, including long-term storage (as a hard drive), a graphics card port, and network ports (including wireless).

Without a motherboard, everything in a computer would be a gigantic tangle of wires. So, while the motherboard isn’t particularly complex, it’s critical to keep everything organized and regulate airflow for heat management.

Failing

Most of the time, the extreme complexity of a motherboard means that it’s the first thing to fail.

Thankfully, it’s also often one of the least expensive parts of a computer.

Clock

Beyond keeping everything organized, motherboards tend to come with a built-in “clock” that oscillates a 0-1-0-1 signal. It’s a bit like a ticking clock, with each 1 as a cycle. All the sequential logic circuits get this signal, and the clock runs at about 200,000,000 times a second (200 MHz).

The clock is typically made of quartz, since quartz resonates at a predictable vibration when electricity runs through it. However, heat can modulate those vibrations, and the inaccuracies from that heat can resonate at upwards of 30 seconds a month. The easiest solution has been to consistently synchronize the time with a time server (NTP protocol).

Designing

To create a computer system, not everything starts with PCBs.

  1. First, the designer needs to understand what circuits are doing, so they need schematics.
  2. Then, they will use “breadboards” to create prototypes of electronic circuits, which don’t require soldering and are completely reusable. The circuits will be low-speed because they’re simply clipped onto the board.
  3. After they know what they’re doing or want something higher-speed, they’ll either use “stripboard” to prototype mid-speed circuits or PCBs for high-speed circuits.
  4. Finally, when they want to build something for commercial use, they’ll use PCBs.

The Gerber format is a convenient alternative to creating something directly on a PCB. It’s an open PCB standard that gives all the instructions necessary for an engineer to manufacture finished computer parts at scale.

The improvements of error-correcting code within processors have made circuit design much more forgiving than in the past.