I don't know TCL at all though I have implemented my own variation of tiny C in a handheld terminal I designed in the past which fitted nicely in 10KB in a PIC1

I don't know TCL at all though I have implemented my own variation of tiny C in a handheld terminal I designed in the past which fitted nicely in 10KB in a PIC18F processor and 3K of RAM for the (compressed) basic so always good to see a different spin on other interpreters. Your code doesn't actually compile in my MPLAB XC8 compiler but should be fixable so I may give it a go. I note there are no comments in the code but the explanation text should help.