I'm Michael Zapf (posting as “mizapf” in the MESS forum). My primary interest is to get a clean, bug-free emulation of the TI-99/4A system.
While we have an emulation of some UART chips, they are all connected to a file as a backend. This means that all write operations go to this file, and input operations … well, so such thing yet. Virtual machine implementations like VMWare include access to real hardware, so this should also be possible here.
An important use case of a connection to a real serial port is to establish a connection between the emulation and the real hardware in order to easily exchange files or to test software that uses serial connections.
There are at least two ways how to implement this:
The second option is attractive for its platform independence.
In the meantime I designed and created an implementation for this serial connection for the TMS9902 UART in the TI RS232 card. It should be possible to refactor it as an own device or slot device, whatever structure is preferred.
The new cartridge definitions for the TI systems can be found on ninerpedia.
It is not trivial to set up the HSGPL; you need a particular loader program. Also, for the SGCPU you need a properly set up HSGPL or it will crash at startup. I collected some instructions and tool to set up an empty HSGPL: HSGPL Setup.
I've recently studied the descriptions to software lists a bit more throughly, and also checked the DTD.
I guess that with more and more systems adopting the lists and less using the RPKs, I (or whoever) will not have another option but to implement them for the TI family as well in not-so-distant future. Still, there are some points which are missing or for which I need some more clarifications: