Guys! The program is now working fine with AT89C52. The unwanted first charachter has disappeared.

Regardless the initialization we discussed earlier,
I just switch :

void ser_putch( unsigned char ch ) {
SBUF = ch;
while ( !TI );
TI = 0;
}

to :

void ser_putch( unsigned char ch ) {
TI = 0;
SBUF = ch;
while ( !TI );
}


Now I can't think of a conclusion :(
The fact is the first version of function did work with AT89C51 but not with AT89C52.

Any comment?