Hi,

I have just started using the 89C51RC+, and attempting to use the ISP feature. All seems to work, except nothing is written to the flash.

Using a terminal, I get the U echo in response to sending a U, from this I assume that the pins etc are in the correct state to evoke the boot loader prog.

Executing set clock rate Intel hex string returns a . so I assume that things are correct.

However, if I send the Intel hex string to set the status byte to zero, then read the status byte, I get 0xFF ?

If using winISP, all seems to work ok unless I try and modify the contents of the flash in any way, I either get programming failed, or the device returns 0xFF?

Any thoughts suggestions appreciated.