jkotlinski / gbchrono

Game Boy Clock Accuracy Challenge

Game Boy Clock Accuracy Challenge

About

The Game Boy Clock Accuracy Challenge is about determining the real clock speed of different Game Boy models.

Background

The Game Boy CPU is specified to run at 4194304 Hz. (Super Game Boy: 4295454.4 Hz NTSC; 4256274 Hz PAL.) While these numbers seem very exact, they are known to be inaccurate. A real Game Boy will run faster or slower. This project measures how fast or slow. The results are kept in a public Google Sheet, free for anyone to use as a reference.

How to Participate

1. Find an accurate stopwatch with subsecond precision (e.g. smartphone, smartwatch, PC).
2. Install gbchrono.gb on a Game Boy flash cartridge.
3. Start your Game Boy. It will beep to tell that is it ready. Prepare your stopwatch.
4. Simultaneously start stopwatch and tap A on Game Boy. The measurement starts when the button is released.
5. Let your Game Boy run overnight (or longer, for increased accuracy). To save battery, it will run with screen and sound disabled.
6. Simultaneously stop stopwatch and tap A on Game Boy. The measurement stops when the button is released.
7. The Game Boy will now show some digits that tell the elapsed time.
8. Enter the data on the Google Sheet.

Example screenshot from step 7

Why Participate?

• It is fun and easy!
• Contribute to Game Boy science!
• Learn the true speed of your Game Boy!