I did a mental simulation, and had a couple of questions that probably would have been fixed if there had been a line of comment for every line of code, which should be the MINIMUM, particularly when the code is not producing what it ought.

I'm curious, too, about the state of DME0 (PMR.0). That also has to be set (true) for the internal XRAM to work, doesn't it?

There are a couple of lines that puzzle me. One loads a 12, presumably decimal, which would, if memory serves, be a formfeed, into A and then calls SendByte, though I don't know what the console does with a formfeed.

The next couple of instructions send a RETURN, so that's understandable.

Then there's that load A with '?' after which the DPTR is zeroed and A loaded with whatever's at the bottom of XRAM. I can't imagine there's any point in loading the '?' into A when the next thing is to load it with whatever's in XRAM(000). That should, of course, be a '!' if the write at the beginning of the code worked. Now, maybe I'm misreading something ...

I'd wonder what it is about this code that makes it clear that it's not working. What's more, I'd be curious what, exactly it was hoped it would do.

See what I mean about comments?

RE