I just found this very little cute BASIC interpreter: Jasic and I decided to make a port to Flash in order to add basic graphics commands (just "setcolor" and "putpixel" actually) so I could see the little thing drawing a colored Mandelbrot fractal. It was very easy, thanks to the profusely commented code of the original author (Bob Nystrom). You can select the program demos from the drop-down menu and press the [Run] button to start the interpreter. So without further ado, Flasic:
It's not that slowly, but being a BASIC interpreter inside a Flex interpreter inside a Flash bytecode interpreter surely takes his toll, oh the irony... :D
The code is my repo, many thanks to the original author for releasing his original version, it was fun.