Game Boy Bootstrap ROM

Game Boy Bootstrap ROM
Developer: Nintendo Publisher: Nintendo Released in JP: April 21, 1989 Released in US: July 31, 1989 Released in EU: September 28, 1990 Released in KR: May 2, 1991 (Hyundai Mini Comboy) This console has revisional differences. This console has a bugs page

The original Game Boy Bootstrap ROM will display a scrolling down "Nintendo" logo before booting the game. If the logo on the Game Pak does not match "Nintendo", the game will typically not run (preventing read errors and trapping some but not all unlicensed games).

Sub-Page

Bugs

Revisional Differences

• Rev 0 (DMG) - A version of the bootstrap ROM limited to some early Japanese Game Boys (only DMG-CPU on the back, others have DMG-CPU A, B, C). The registered trademark symbol (®) is omitted from the company logo (usually "Nintendo" from the Game Pak header). If there is a Game Pak read error, the LCD may simply flash on and off without scrolling the logo down and the game will not run.
• Rev 1 (DMG) - The boot ROM used in most Game Boys. It added the ® to the top-right of the company logo. If there is a Game Pak read error (such as a bad company logo), unlike Rev 0 the 'logo' will scroll down as usual, but the game will not run.
• Pocket Game Boy (MGB) - In this revision, before control is handed over to the game the a register is written as 0xFF instead of 0x01. A game can retrieve this byte to distinguish if the hardware is DMG (01) or MGB (FF).

(Source: gbdev.gg8.se, Game Boy hardware database, Torchickens ("®" detail))