Microchip Technology MA180025 データシート
2010 Microchip Technology Inc.
DS39933D-page 65
PIC18F87J90 FAMILY
6.0
MEMORY ORGANIZATION
There are two types of memory in PIC18 Flash
microcontroller devices:
• Program Memory
• Data RAM
As Harvard architecture devices, the data and program
memories use separate busses; this allows for
concurrent access of the two memory spaces.
Additional detailed information on the operation of the
Flash program memory is provided in Section 7.0
“Flash Program Memory”.
microcontroller devices:
• Program Memory
• Data RAM
As Harvard architecture devices, the data and program
memories use separate busses; this allows for
concurrent access of the two memory spaces.
Additional detailed information on the operation of the
Flash program memory is provided in Section 7.0
“Flash Program Memory”.
6.1
Program Memory Organization
PIC18 microcontrollers implement a 21-bit program
counter which is capable of addressing a 2-Mbyte
program memory space. Accessing a location between
the upper boundary of the physically implemented
memory and the 2-Mbyte address will return all ‘0’s (a
NOP
counter which is capable of addressing a 2-Mbyte
program memory space. Accessing a location between
the upper boundary of the physically implemented
memory and the 2-Mbyte address will return all ‘0’s (a
NOP
instruction).
The entire PIC18F87J90 family offers a range of
on-chip Flash program memory sizes, from 64 Kbytes
(up to 16,384 single-word instructions) to 128 Kbytes
(65,536 single-word instructions). The program
memory maps for individual family members are shown
in Figure 6-1.
on-chip Flash program memory sizes, from 64 Kbytes
(up to 16,384 single-word instructions) to 128 Kbytes
(65,536 single-word instructions). The program
memory maps for individual family members are shown
in Figure 6-1.
FIGURE 6-1:
MEMORY MAPS FOR PIC18F87J90 FAMILY DEVICES
Note:
Sizes of memory areas are not to scale. Sizes of program memory areas are enhanced to show detail.
Unimplemented
Read as ‘0’
Unimplemented
Read as ‘0’
000000h
1FFFFFh
01FFFFh
00FFFFh
PC<20:0>
Stack Level 1
Stack Level 31
CALL, CALLW, RCALL,
RETURN, RETFIE, RETLW,
RETURN, RETFIE, RETLW,
21
Us
er M
e
mo
ry
S
pace
On-Chip
Memory
On-Chip
Memory
ADDULNK, SUBULNK
Config. Words
Config. Words
PIC18FX6J90
PIC18FX7J90