yup, that's for sure Bruce, this is why i plan to do my own terminal program for some 'specific' purpose.

Send a packet to PIC, PIC send 'ok' (or whatever else), once PC receive it, send next packet, and so on. That imply to build our own program instead of using CTS/RTS DTR/DSR with already made terminal program. AND we save i/o for handshaking.