1. P89V51RD2 has no boot vector, so there is nothing you can lose
2. The usual debug chain:
- get an oscilloscope
- always measure DIRECTLY at the mcu's pins
- verify the P89V51RD2 has proper power (at the mcu's pins)
- verify that oscillator is running
- verify that reset is not held high
- run a terminal program on PC and transmit Us continuously from it (assuming it is properly set, the appropriate port, speed 4800-9600, 8N1). E.g. if you use Hyperterminal, switch on CapsLock and press and hold U, the autorepeat takes care for you. Better, download term by Bray, it's free and it can repeatedly transmit a sequence in a given time interval.
- verify, the Us get through your RS232-to-5V level convertor to the RxD pin
- reset the mcu and check if it starts echoing the Us on the TxD pin
- if yes, you should see Us echoing on the terminal's screen (assuming local echo is off)
- if yes, install FlashMagic and learn how to use it.

If any item in this chain fails and you don't know what does that mean, get back here.

Jan Waclawek