PocketNES is an NES emulator which runs on the Game Boy Advance, written by Neal Tew (Loopy) and Fredrik Olsson (Flubba). It can run on a GBA through use of flash cartridges, or with the GBA Movie Player. The emulator has been released into the public domain, yet it remains under active development.
More than a year after the first release of PocketNES, Nintendo re-released several of their NES games on the GBA through the e-Reader accessory, Animal Crossing GameCube game link feature, or Classic NES Series collection. Since PocketNES predates all of Nintendo's efforts, it is believed that PocketNES was the inspiration for Nintendo to create their own similar emulator.
NES gameplay issues
The GBA screen has a lower vertical and horizontal resolution than the NES's display. PocketNES compensates by either scaling the image down vertically, or by scrolling the image up or down. Such scrolling can either happen automatically, following the position of a sprite or value of a memory address, or manually using the GBA's L and R buttons. Sound is reproduced via the "classic" Game Boy PSG channels, rather than a software emulation of the NES's sound hardware; this is done to reduce CPU usage. As a result, it does not sound exactly like the original NES, although it is a close approximation.
PocketNES's source code is in the public domain, which means that it can be used for any purpose, without any royalty or permission necessary (as it purposely has no copy protection). As a result, it has been used by game publishers and pirates alike. None of the companies have credited the original authors of the program, with exception of Wayforward Technologies in Contra 4 published by Konami.
Atlus (or more specifically, Million) used PocketNES in the Kunio kun Nekketsu Collection series to re-release Technos's Famicom titles on the GBA. They released three different volumes, each containing two games.
- Volume 1 contains Nekketsu Kōkō Dodgeball Bu (Super Dodge Ball overseas) and Nekketsu! Street Basket - Ganbare Dunk Heroes.
- Volume 2 contains Downtown Nekketsu Kōshinkyoku: Soreyuke Daiundōkai and Nekketsu Kōkō Dodgeball Bu - Soccer Hen (Nintendo World Cup overseas).
- Volume 3 contains Downtown Special: Kunio-kun no Jidaigeki da yo Zen'in Shūgō! and Ike Ike! Nekketsu Hockey Bu: Subette Koronde Dairantō (the unreleased Crash 'n the Boys: Ice Challenge in North America).
- Volume 1 contains Bomberman and Bomberman II.
- Volume 2 contains Lode Runner and Championship Lode Runner.
- Volume 3 contains Challenger and Milon's Secret Castle.
- Volume 4 contains Nuts and Milk, Binary Land, and Princess Tomato in the Salad Kingdom.
- Volume 5 contains Star Force, Star Soldier, and Hector'87.
- Volume 6 contains the four Adventure Island games.
The credits in Contra 4, by developer WayForward Technologies, thank the authors for the "original PocketNES software core". It was most likely used to emulate the NES versions of Contra and Super C included within the game as bonus content.
PocketNES has been ported to Nintendo DS and is called nesDS. This version uses the DS touch screen as a menu, allowing players to touch the screen to go into the menu.
-  Claim that PocketNES inspired Nintendo's NES on GBA rereleases with timeline evidence
-  Contra 4 credits via Moby Games
-  Pocket Heaven thread on Atlus's use of PocketNES
-  Pocket Heaven thread on Hudson's use of PocketNES.
-  Discussion on the use of PocketNES in Contra 4 and using the Contra 4 ROM to emulate other NES games
-  Pocket Heaven thread about the Nintendo patent