[classichasclass]

(author) I thought AS worked pretty well. The syntax is a little idiosyncratic but it "just worked" once I learned its pet peeves, and it seems to have specific support for the added 9995 instructions.

[cpswan]

Have you found your way to Stuart Conner's page? http://www.stuartconner.me.uk/

Lots of resources on the original TI dev boards and tools for TMS99Xx.

[nickt]

Thank you, that’s a great site. There goes my Sunday morning!

[bitwize]

I used AS to write the program, and it is my "reference assembler" for the one I am writing. I just wanted to see if I could write a working retro assembler.