Eric,
I have no arguments with you regarding manually setting an interrupt flag, I would have thought that sending a character to SBUF should suffice. In Marco's code, however, it looks as though he never clears the Ti bit in the interrupt routine. If I understand the data on SCON, both Ri and Ti have to be reset by the software. Unlike the other interrupt vectors, entering the Ri + Ti vector does not clear the interrupt flag.

Appreciate your help

Hal