Virtual GameBoy is a program that emulates the Nintendo GameBoy handheld on your computer. It runs GameBoy, Super GameBoy, and GameBoy Color games on PCs, Macs, PocketPCs, Unix boxes, etc. VGB also helps debugging GameBoy software without using a costly development system.

Virtual GameBoy v5.6 Changelog:

Fixed RTC day of the week calculation (Pokemon games).
http://fms.komkon.org/VGB/