PIC18F452-IPT Datasheet, PDF (37/332 Pages) Microchip Technology – High-Performance, Enhanced Flash Microcontrollers with 10-Bit A/D

4.0 MEMORY ORGANIZATION
There are three memory blocks in Enhanced MCU
devices. These memory blocks are:
• Program Memory
• Data RAM
• Data EEPROM
Data and program memory use separate busses,
which allows for concurrent access of these blocks.
Additional detailed information for FLASH program
memory and Data EEPROM is provided in Section 5.0
and Section 6.0, respectively.
4.1 Program Memory Organization
A 21-bit program counter is capable of addressing the
2-Mbyte program memory space. Accessing a location
between the physically implemented memory and the
2-Mbyte address will cause a read of all ’0’s (a NOP
instruction).
The PIC18F252 and PIC18F452 each have 32 Kbytes
of FLASH memory, while the PIC18F242 and
PIC18F442 have 16 Kbytes of FLASH. This means that
PIC18FX52 devices can store up to 16K of single word
instructions, and PIC18FX42 devices can store up to
8K of single word instructions.
The RESET vector address is at 0000h and the
interrupt vector addresses are at 0008h and 0018h.
Figure 4-1 shows the Program Memory Map for
PIC18F242/442 devices and Figure 4-2 shows the
Program Memory Map for PIC18F252/452 devices.
PIC18FXX2
© 2006 Microchip Technology Inc.
DS39564C-page 35