In a recent blog update and YouTube video, indie game developer Matt Greer unveiled his impressive feat of squeezing an entire game of Solitaire onto a single custom Nintendo e-Reader card. This card holds two “dotstrips” with 2,192 bytes each, adding up to just over 4.3 kilobytes in total.
The Nintendo e-Reader, introduced with the Game Boy Advance in December 2001 in Japan and September 2002 in the US, was a nifty gadget. It allowed players to scan cards to load full games or add-ons for existing Game Boy Advance games onto its generous 8MB internal storage. Back in the day, some games, especially NES ports, required up to 10 cards, and the system could handle as many as 12. For reference, adding extra levels to Super Mario Advance 4 needed just one card.
In his detailed blog post on the project, Greer dives into the technical challenges of crafting this unique homebrew version of Solitaire. He tackled one of the strictest technical environments imaginable for Game Boy Advance titles. While homebrew games for the GBA are already pretty niche, creating one that fits on a single e-Reader card is almost mind-bogglingly unique.
According to Greer’s original write-up, the e-Reader could load NES games, raw binaries, and even Zilog Z80 binaries. The Z80 assembly, with its minimal footprint, proved ideal for this project. The e-Reader also offered an API (ERAPI) that enabled developers to perform common tasks directly from the device instead of coding them into the dotstrip, saving valuable space.
He mentions a crucial limitation: the Z80 emulator on the e-Reader isn’t fully accurate and manages a limited set of operations and registers. This means some typically feasible actions on a Z80 aren’t doable here. Nevertheless, Greer navigated these restrictions to create a playable Solitaire game with changeable music, all within 4,384 bytes. Achieving this across two dotstrips on a single e-Reader card is an incredible testament to his skill. It’s a shame that e-Reader cards had such a short production run, and the device itself has largely faded into the annals of gaming history.
