🎵 It's beginning to look a lot like... a TRS-80 MC-10 🎵 (wat? why?)
I think this was Tandy's answer to the cheap ZX81/VIC-20. Very limited, not much ram (4K, 20K max). Not really compatible with the other colour computers. You can guess it was not a big hit.
Still, I had a 6800 CPU emulation laying around (this one uses a 6803, which is a 6800 + 128bytes ram + io ports integrated), and I wanted to start working on the MC6847 video chip (used in CoCos and such) so why not.
Pour les amis Francais, c'est le Matra Alice (même mécanique avec un joli boitier rouge et un clavier AZERTY)
The good news is that chasing this bug only took me *mumble* hours!
Thanks to the MC-10 BASIC instruction parsing code for using the stack pointer in a... creative... manner (to be fair what they are doing is 100% legal)
Basically (get it?) they are using the stack pointer as an index for the line being parsed because the index register is already busy going through the token table. That's pretty neat.
So the BASIC actually basics now, which I hear is a good thing as far as basicing is concerned.
Legally Zoé