UPD78F4046GC-3B9 NEC, UPD78F4046GC-3B9 Datasheet - Page 16

• Manufacturer Part Number: UPD78F4046GC-3B9
• Description: 16-BIT SINGLE-CHIP MICROCONTROLLER
• Manufacturer: NEC

6. INTERNAL MEMORY SIZE SWITCHING REGISTER (IMS)
be used. By setting this register, the internal memory of the PD78F4046 can be mapped identically to that
of a mask ROM version with a different internal memory (ROM and RAM) capacity.
versions.
16
IMS is a register that is set by software and is used to specify a part of the internal memory that is not to
IMS is set with an 8-bit memory manipulation instruction.
RESET input sets IMS to DEH.
Table 6-1 shows the IMS setting values to make the memory mapping the same as that of the mask ROM
Address: 0FFFCH
IMS
Table 6-1. Setting Values of Internal Memory Size Switching Register (IMS)
Note
PD784044, 784054
PD784046
Figure 6-1. Internal Memory Size Switching Register (IMS) Format
7
1
Target Mask ROM Version
When IMS is set to CDH, the peripheral RAM capacity of the
512 bytes. Consequently, when making a mask ROM version, be
sure not to use 0FA00H through 0FAFFH in the peripheral RAM area
of PD78F4046 (upon the execution of the LOCATION 0H instruc-
tion).
PD78F4046 is 768 bytes, but that of the PD784044 or 784054 is
Other than above
Other than above
ROM1
RAM1
6
1
0
0
0
1
After reset: DEH
ROM1
ROM0
RAM0
5
0
1
1
0
Data Sheet U11447EJ2V0DS00
32 KB
64 KB
Setting prohibited
768 bytes
1.5 KB
Setting prohibited
ROM0
4
CDH
DEH
Peripheral RAM Capacity Selection
Internal ROM Capacity Selection
Note
3
1
R/W
IMS Setting Value
2
1
RAM1
1
RAM0
0
PD78F4046