I've been doing a little research on the API call 0FFF0H to IAP flash. After reading some of the previous posts there were a couple of things that were not clear to me. First, I am programming the Atmel AT89C51RC2.

1) Some code examples I've seen floating around show the loading of R0 with a value that somehow translates to FOSC. Is that necessary to do on the AT89C51RC2? I am not seeing in the documentation how to determine this value and the ATMEL documentation does not show the need for this.

2) Atmel posts examples on how to envoke an API call.
http://www.atmel.com/dyn/resou...oc4365.pdf
It is in C but it is not that hard to read. In the examples they appear to turn off interrupts before writing to flash. Maybe I am looking at the wrong documentation but I haven't seen the need to turn off interrupts documented anywhere in Atmel datasheets - although that maybe the source of a problem I am currently experiencing. Do interrupts need to be turned off when writing to flash?