Can you explain a bit more why including jnb RI,$ in the interrupt handler won't work? Actually this does work fine on port 0. I just can't get it to work on port 1. Since interrupts on the port are turned off within the interrupt handler, why can't I use this "wait for RI" approach?
when hanging in an ISR waiting for a character to receive you just HANG. Anything else in your code the main loop, other ISRs, ... all come to a complete stop. While this may work for 'experimenting' it is almost guaranteed to leave debris behind that will totally screw you up with a small nagging once a day failure when you have "cleaned it up"

correcting your language"
Actually this 'works' on port 0 maybe it SEEMS to

I have seen waaaaaaaaay too many problems in final products stemming from 'experimenting' being done in a "it does not matter for the experiment" way.

the only uses of RI, TI and SBUF in the ISR should be:

jbc RI,received
jbc TI,transmitted
jmp exit
received:
... no RI, NO TI possibly a mov SBUF,
jmp exit
transmitted:
... no RI, NO TI possibly a mov SBUF,
exit:

Erik