https://github.com/meithecatte/mbc3-fiddle

Game Boy ROM for RTC tests and exploration
https://github.com/meithecatte/mbc3-fiddle

Last synced: 7 months ago
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Game Boy ROM for RTC tests and exploration

• Host: GitHub
• URL: https://github.com/meithecatte/mbc3-fiddle
• Owner: meithecatte
• Created: 2020-08-06T14:25:16.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2020-08-06T21:43:19.000Z (over 5 years ago)
• Last Synced: 2025-04-05T05:51:10.277Z (11 months ago)
• Language: Assembly
• Size: 23.4 KB
• Stars: 9
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
# MBC3 RTC Fiddle

This is a simple Game Boy ROM that lets you play around with the Real Time Clock

registers, originally developed to debug the implementation used by the EZ Flash Junior.

You can grab a ROM [on the releases tab](https://github.com/NieDzejkob/mbc3-fiddle/releases).

## Functionality

![](screenshot.png)

At the top, the current values of the RTC registers are shown, starting with

`DAY_HIGH ($0C)` on the left. They are updated every frame (which means the

bank select register is cycled 60 times a second), but by default you have to

latch the registers manually.

SELECT toggles between writing values and latching the registers (indicated by

the arrow on the left).

When writing values:

 - UP/DOWN to change the value

 - LEFT/RIGHT to change the address and the digit you're modifying

 - A to write the byte

When latching:

 - LEFT to write a 0

 - RIGHT to write a 1

 - START to switch to automatic latching. It will get disabled once you press

   LEFT or RIGHT again.

The value last written to the latch register is highlighted.