PD78F0066_15 Datasheet, PDF (16/30 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCONTROLLER

µPD78F0066
3. MEMORY SIZE SWITCHING REGISTER (IMS)
This register sets a part of internal memory unused by software. The memory map can be made the same as
that of mask ROM versions with different types of internal ROM capacities by setting the memory size switching
register (IMS).
IMS is set with an 8-bit memory manipulation instruction.
RESET input sets IMS to CFH.
Caution
To initialize the program, be sure to set IMS to the value shown in Figure 3-1. Also be sure
to set IMS to the value shown in Figure 3-1 after resetting, because reset input sets IMS to
CFH.
Figure 3-1. Format of Memory Size Switching Register
Symbol 7
6
5
4
3
2
1
0
Address After reset R/W
IMS RAM2 RAM1 RAM0 0 ROM3 ROM2 ROM1 ROM0 FFF0H
CFH
R/W
ROM3 ROM2 ROM1 ROM0 Selection of Internal ROM Capacity
1
0
1
0 40 Kbytes
1
1
0
0 48 Kbytes
Others
Setting prohibited
RAM2 RAM1 RAM0 Selection of Internal High-speed RAM Capacity
1
1
0 1024 bytes
Others
Setting prohibited
Table 3-1 shows the IMS set value to make the memory map the same as those of mask ROM versions.
Table 3-1. Set Value of Memory Size Switching Register
Target Mask ROM Versions
µPD780065
IMS Set Value
CAH
14
Preliminary Product Information