Having asm sources would allow a direct port to z80
I'm afraid that you're being too optimistic here 
I started with ti 99/4a before moving to MSX. Been trying to buy a TI but they are expensive. I remember a game, I think in basic, where there were 9 'houses' and you had to move to them but you could not cross your earlier path. Any TI user know what game that is? Every house had a number inside it and your sprite would leave a trace in a different color.
I had a ti 99/4a in 1984 or something, there were still games being sold but very expensive. Most games were on cartridge and I used a black and white tv for it 
So I never realized there was a tileviewer command in openmsx... Very neat feature for debugging!!
Unfortunately I just tried it in openmsx 0.15.0 and I get an error message "invalid command name".
Am I missing something?
