there are two files I've been referencing for information about the TI-86's ports... both from ticalc.org (todo: link em)

One covers "all" ports, 0-7. The other goes into some detail about port 4. (Was there a third?)

I was looking to try to find how the absolute addressing is handled (does it involve a port-write of A23-16?) and came across "86inc" which attempts to combine numerous include files into one... Under the Ports section there's a Port 11(?) "iall" "interrupts on, lcd on"... (actuall, after MUCH searching, I think that may actually be a value to load into port3?)

Well, the rabbit hole went so far as finding port 11 in the emulator 'tilem' source code. Which is used on the TI-83 and others to configure the LCD controller, and some weirdness that led me to believe the same LCD controller might be embedded into the CPU in the 86... and... I was pretty durn convinced for quite some time, but now I'm not.... as of just seconds ago while writing this. Heh.

That said, I suppose looking into an emulator's sourcecode could tell one a lot about nitty gritty like the memory mapping system hardware... brain (and technology) is /definitely/ not there for that.