Mitsubishi microcomputers
M16C / 62 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Memory Space Expansion Functions
21
Memory Space Expansion Features
Here follows the description of the memory space expansion function.
With the processor running in memory expansion mode or in microprocessor mode, the memory space
expansion features provide the means of expanding the accessible space. The memory space expansion
features run in one of the three modes given below.
(1) Normal mode (no expansion)
(2) Memory space expansion mode 1 (to be referred as expansion mode 1)
(3) Memory space expansion mode 2 (to be referred as expansion mode 2)
Use bits 5 and 4 (PM15, PM14) of processor mode register 1 to select a desired mode. The external
memory area the chip select signal indicates is different in each mode so that the accessible memory space
varies. Table 1.8.1 shows how to set individual modes and corresponding accessible memory spaces. For
external memory area the chip select signal indicates, see Table 1.12.1 on page 33.
Table 1.8.1.
The way of setting memory space expansion modes and corresponding memory spaces
Expansion mode
How to set PM15 and PM14
0, 0
1, 0
1, 1
Accessible memory space
Up to 1M byte
Up to 1.2M bytes
Up to 4M bytes
Normal mode (no expansion)
Expansion mode 1
Expansion mode 2
Here follows the description of individual modes.
(1) Normal mode (a mode with memory not expanded)
‘Normal mode’ means a mode in which memory is not expanded.
Figure 1.8.1 shows the memory maps and the chip select areas in normal mode.
Figure 1.8.1. The memory maps and the chip select areas in normal mode
Microprocessor mode
F8000
16
F0000
16
E8000
16
E0000
16
AAAAA
AAAAA
AAAAA
AAAAA
AAAAA
AAAAA
AAAAA
SFR area
Internal RAMarea
Internal area reserved
00000
16
00400
16
XXXXX
16
YYYYY
16
FFFFF
16
D0000
16
Note 1: These memory maps show an instance in which PM13 is set to 0; but in the case of M30624MG/FG, they show an
instance in which PM13 is set to 1.
Note 2: The memory maps in single-chip mode are omitted.
08000
16
AAAAA
Memory expansion mode
AAAAA
AAAAA
AAAAA
AAAAA
AAAAA
SFR area
Internal RAM area
Internal ROM area
Internal area reserved
Internal area reserved
CS3
(16K bytes)
CS2
(128K bytes)
CS1
(32K bytes)
CS0
Memory expansion mode: 640K bytes
Microprocessor mode: 832K bytes
28000
16
30000
16
04000
16
Normal mode (memory area = 1M bytes for PM15 = 0, PM14 = 0)
M30622M4
M30620M8
M30620MA
M30620MC/EC
00FFF
16
02BFF
16
02BFF
16
02BFF
16
C0000
16
053FF
16
M30624MG/FG
E8000
16
E0000
16
017FF
16
017FF
16
M30622MA
M30622MC
M30622M8/E8
F0000
16
013FF
16
Address XXXXX
16
Type No.
Address YYYYY
16