I've got some questions on the basic operation of the 8051 regarding the /EA pin.
According to Atmel's AT89C51 datasheet, /EA is to be strapped to Ground to enable fetching from external program memory. It should be strapped to Vcc for internal program execution.
So if the /EA pin is low (Gnd), all internal Flash Program Memory is ignored? If /EA is high (Vcc), only the internal Flash Program Memory is used. How does the 8051 use both internal and external then?
I saw that Erik mentioned how once you access code addresses past the internal space that the 8051 will "roll-over" into the external space. This seems to go against the datasheet, or is internal program memory always enabled? (I guess this would imply that /EA simply controls whether external program memory exists beyond the internal space)
I'd love to use this idea to place my low level architectural things like my scheduler into internal and all application specific routines in external. Since I write only in assembler, could I just ORG all application specific code to an address larger than the internal space?
Thanks for the help.
Chris