ORGANIZATIONAL PROGRAM MEMORY
Programming memory of 89c51 can be applied to 64 KB long( program memory instruction code (ROM)) Data memory ( user data (RAM)).
This because address line is 16 bit .so 2^16=65536=64KB.the program counter can address location from 0000H to FFFFH . Internal ROM or on chip flash ROM has a capacitive addressing from 0000H to 0FFFH (4K). If the program address exceed 0FFFH .Then 89c51 automatically fetches the code bytes from external program memory(from 1000H to FFFFH).Another options is to use external program
memory along code byte can be fetch exclusively from external program memory address ranging from 0000H to FFFFH.
if EA bar pin connected to VCC , the program codes are fetched from internal ROM ( 000H - 0FFFH) + external ROM ( 1000H - FFFFH ) . If EA bar = 0, codes are fetched from external memory only.
<---------thank you-------------->Labels: ATMEL 89C51
