jTandy is a TRS-80 model III emulator written in javascript. It has the same philosophy that jBacteria, Roland and jupiler, that is: The emulator is developed by Antonio Villena and Peter Phillips. The games are extracted from Planet Emulation. The license is GPLv3, so you have access to the source code, but your derived software must be GPL too and do mention to the authors.

Update: (2 sept 2012) Andy Warren notice me a bug in Y and Z keys with detailed instructions to solve it. Thanks Andy.

my email is anyone at antoniovillena.es