hi guys, thanks for all your advices and sugestions, specially to Hal & Mr. Kumar. In the simulator all runs ok, but still I can see none signal at pin P3.0 or P3.1.(they always are in on ). I try a program gived for Mr. Kumar to test the microcntroller, with this program I can use my computer like hyperterminal (with Windows 98) and test if the microcontroller is working because it transmit some character from input go throught microcontroller and display in hyperterminal screen. I tested MA232, is working good. I disconected the rest of the circuit and now I ma just working with the minimum system, and still the problem is present. I am using AT89C52 from ATMEL, is the same than 8052, I am using too a 11.059 Mhz crystal to generate a baud rate that match (9600 bps), with serial port settings. I checked again the wires at protoboard, that's correct. Really I don't know what to do now. As a matter of fact, is enough write to SBUF to activate the flags and the pulses begin to go out by P3.1 TXD.
Someone of yours had some trouble with 8052 and serial port transmision ?