Forum,
I've recently started using the T89C51RD2-EM uC. The procedure I use is as follows:

Short PSEN to ground
perform hardware reset
Start FLIP 1.6.0 and connect to uC
program and verify uC
remove PSEN to ground jumper
perform hadware reset

At this point my program is up and running with no problems. The program displays a cycle count on an LCD.

Problem: After powering off my project and re-powering up, the target program appears to work correctly, except the counter starts at a very high count. It is a 16 bit counter using ram locations 3BH and 3CH, these are set to zero before starting the cylces. It appears that location 3BH (the high byte) is getting clobbered some how.
Now, if I short PSEN to ground and do the hardware reset, then unshort PSEN and do a hardware reset (no chip programming), it will work correctly until power is cycled on and off again.

I've searched this website and have yet to find the answer in the data sheet, it may be there but I haven't found it yet.

As I stated before this target program gives no problems with AT89C52 and I haven't made any changes specifically for the T89C51RD2.

Does anyone know the answer off the top of their head?

Thanks in advance.
Jon