PIC18F2220/2320/4220/4320
5.1
Program Memory Organization
5.0
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).
There are three memory types in Enhanced MCU
devices. These memory types are:
• Program Memory
• Data RAM
• Data EEPROM
The PIC18F2220 and PIC18F4220 each have
4 Kbytes of Flash memory and can store up to 2,048
single-word instructions.
Data and program memory use separate busses which
allow for concurrent access of these types.
Additional detailed information for Flash program mem-
ory and data EEPROM is provided in Section 6.0
“Flash Program Memory” and Section 7.0 “Data
EEPROM Memory”, respectively.
The PIC18F2320 and PIC18F4320 each have
8 Kbytes of Flash memory and can store up to 4,096
single-word instructions.
The Reset vector address is at 0000h and the interrupt
vector addresses are at 0008h and 0018h.
The Program Memory Maps for PIC18F2220/4220 and
PIC18F2320/4320 devices are shown in Figure 5-1
and Figure 5-2, respectively.
FIGURE 5-1:
PROGRAM MEMORY MAP
AND STACK FOR
FIGURE 5-2:
PROGRAM MEMORY MAP
AND STACK FOR
PIC18F2220/4220
PIC18F2320/4320
PC<20:0>
PC<20:0>
21
21
CALL,RCALL,RETURN
RETFIE,RETLW
CALL,RCALL,RETURN
RETFIE,RETLW
Stack Level 1
Stack Level 1
•
•
•
•
•
•
Stack Level 31
Stack Level 31
0000h
0000h
Reset Vector
Reset Vector
High Priority Interrupt Vector
Low Priority Interrupt Vector
High Priority Interrupt Vector
Low Priority Interrupt Vector
0008h
0018h
0008h
0018h
On-Chip
Program Memory
On-Chip
Program Memory
0FFFh
1000h
1FFFh
2000h
Read ‘0’
Read ‘0’
1FFFFFh
200000h
1FFFFFh
200000h
2003 Microchip Technology Inc.
DS39599C-page 53
MICROCHIP [ MICROCHIP ]
