So, I've started doing the basic interpreter and I've pulled in my old lexical analysis class. It dates back to when I was doing a 65816 assembler (for the SNES) on the Amiga, and its been ported and updated over the years. It lets me jump into the deep end on these kinds of projects, without having to write yet another lex processor.
So, this looks like it'll be fairly easy and fairly good fun. So I need to start thinking about how I want to handle stacked variables and procedure calls etc.The basic construction is simple a memory block with an overlayed stack system and this give me a call stack as well.
I've also been thinking on the graphics interface and the virtual screen/sprite system. I think having simple SPRITE, TILE and PLAYFIELD system should give everything you need to make some fun games. Kind of like BBC Basic on a SNES, which is a good goal to aim for I think.