Now, I have never used this particular part. But it has certain similarities to the NXP P89C51RD2 series.

It is designed to be in-system-programmable, and as far as I know, both the NXP parts and Atmel parts work just fine. NXP uses FlashMagic and Atmel uses FLIP to communicate with the factory bootloaders.

If I "built" a AT89C51RB2 "circuit", and found that it did not work, I would check my "build" quality.

No doubt, it may well be 'parallel programable'. But it is a bit like changing the engine of a motor car rather than looking for the petrol filler cap.

Both Flip and FlashMagic work. Both require the chip to go into "bootloader" mode. Generally by creating a 'hardware condition'. If you cannot get either program to perform as it says in its manual, the trick is to read the manual a little more carefully.

As I said earlier, I have no personal experience of this chip. It may well be that none of the thousands of chips manufactured have ever worked.

David.