Datasheet

© 2007 Microchip Technology Inc. DS39605F-page 41
PIC18F1220/1320
5.0 MEMORY ORGANIZATION
There are three memory types in Enhanced MCU
devices. These memory types are:
• Program Memory
• Data RAM
• Data EEPROM
Data and program memory use separate busses,
which allows 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.
FIGURE 5-1: PROGRAM MEMORY MAP
AND STACK FOR
PIC18F1220
5.1 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 PIC18F1220 has 4 Kbytes of Flash memory and
can store up to 2,048 single-word instructions.
The PIC18F1320 has 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 the PIC18F1220 and
PIC18F1320 devices are shown in Figure 5-1 and
Figure 5-2, respectively.
FIGURE 5-2: PROGRAM MEMORY MAP
AND STACK FOR
PIC18F1320
PC<20:0>
Stack Level 1
•
Stack Level 31
Reset Vector
Low Priority Interrupt Vector
•
•
CALL,RCALL,RETURN
RETFIE,RETLW
21
0000h
0018h
On-Chip
Program Memory
High Priority Interrupt Vector
0008h
User Memory Space
1FFFFFh
1000h
0FFFh
Read ‘0’
200000h
PC<20:0>
Stack Level 1
•
Stack Level 31
Reset Vector
Low Priority Interrupt Vector
•
•
CALL,RCALL,RETURN
RETFIE,RETLW
21
0000h
0018h
2000h
1FFFh
On-Chip
Program Memory
High Priority Interrupt Vector
0008h
User Memory Space
Read ‘0’
1FFFFFh
200000h