My (current) design will be located in places that are not very accessible. I am therefore considering the following method of "in application programming" of the Philips P89C51RD2:
From the application program : 1)change the status byte 2) set a hardware latch which provide Vpp (through a mosfet/by a logical 1 from a 74s chip) 3) use the watchdog to force a reset 4) use the Philips PC software to program the chip ending with changing the status byte and a power off.
Has anyone done a similar succesful design - or failed and ended up with hardware switches ?

in advance, thanks

Erik