Yes,,,,,as long as you put a voltage level translator such as MAX232 chip between the PC cable connection and the Tx & Rx lines of the 89C52. The PC lines will swing from something like +/- 9 volts to +/- 12 volts. The pins at the 89C52 require voltage swings in the range of 0 -> 5 volts. There is also an need to logically invert the signal polarity too. The MAX232 chip (and others like it) do the inversions for you. This means that when the PC cable line is at +9 -> +12 volts the 89C52 pin level is 0 volts, and when the PC cable line is at -9 -> -12 volts then the corresponding level at the 89C52 is +5 volts.

Michael Karas