If output of the serial link your PC is functional, you get the ASCII
character 20H, at input pin 10 of your 8052. You can see the trace with
a normal scope when you press the space bar of your keyboard. This
is very fast, but the signal toggle. The 8052 determine automaticaly
the baud rate from the temporal caracteristics of space character.

Have you connected the control lines of your DB9 PC connector, to get
only RxD and TxD (soft control protocol) ? You must connect the lines :
1-6-4 and 7-8 together, to conform with the software protocol.

Use the Terminal utility of WIN 3.1 wich is lesser lunatic than his
follower for WIN95/98. With Microsoft, the older is already better !