How the GBA knows it’s running a GB Game

Modern Vintage Gamer recently posted a video about how the Game Boy Advance knew when a Game Boy / Game Boy Color game was being inserted.  The quick answer is GBA carts toggle a physical switch that enabled GBA mode, however this video goes into detail about the software side of things…including how GBC games could run in “GBA Enhanced modes”, even when the GBA mode was toggled.

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As a note, the physical switch issue is also why a ROM Cart like the GBA Everdrive can’t run in a GBC mode:  While technically you could make a cart with pins on both sides, or even some complicated mechanical toggle, this would result in a product that’s far more expensive and don’t look anything like an original GBC/GBA cart.  There’s also the voltage issue to deal with and while that’s solvable, it’s yet another cost.  It’s much more cost-effective for both the designer and consumer to just get one of each:

EverDrive GB X3

 (57)

SUPPORTS 99% Game Boy and Game Boy Color games INSTANT LOADING SUPPORTED MAPPERS: MBC1, MBC2, MBC3, MBC5 LOW POWER CONSUMPTION OS supports up to 1000 files per folder

(as of July 22, 2021 – More infoProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.)

EverDrive GBA X5 Mini

 (79)

$109.00

HIGH COMPATIBILITY. Almost 100% GBA games are supported. ALL SAVES TYPES SUPPORTED, no ROM patching required FAST LOADING (most games load within 1 – 2 seconds) REAL-TIME CLOCK SUPPORT Micro SD cards are supported. Tested with micro-SD cards up to 64… read more

(as of July 22, 2021 – More infoProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.)

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