that is your problem. PSEN must be low or it won't go into boot mode. Now I am not 100% sure on the Phillips MCU's because I only have used atmel.
This is the only way I have been able to get into boot mode with the RD2's and ED2's made by atmel:
Power off your board.
PSEN LOW (use a jumper or switch)
Reset must have RC circuit, (i.e. 8.2K resistor from RST to GND, 10uF cap from reset to VCC)
P2.6 and P2.7 left floating or high whatever, just NOT LOW,
power it up.
Send the "U", you should be "IN".
If not, there may be other problems, like maybe your com port, baud rate, etc.
On the really, really, really old atmels, the bootloader was in the flash memory. If you did a full erase, the bootloader would be erased then you are SOL!! (unless of course you have a parallel programmer to restore the bootloader code)
Try it and post your results.
Good Luck