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CHAPTER 22 EXTERNAL DEVICE EXPANSION FUNCTION
(2) Memory size switching register (IMS)
This register specifies the internal memory size. In principle, use IMS in a default status. However, when
using the external device expansion function with the
µ
PD78058F, 78P058F, 78058FY and 78P058FY, set
IMS so that the internal ROM capacity is 56 Kbytes or lower.
IMS is set with an 8-bit memory manipulation instruction.
RESET input sets this register to the value indicated in Table 22-3.
Figure 22-3. Memory Size Switching Register Format
Note The values after reset depend on the product. (See Table 22-3)
Table 22-3. Values When the Memory Size Switching Register Is Reset
Part Number Reset Value
µ
PD78056F, 78056FY CCH
µ
PD78058F, 78058FY CFH
1
1
48 Kbytes
56 Kbytes
1
1
0
1
0
0
7
RAM2
Symbol
IMS
6
RAM1
5
RAM0
4
0
3
ROM3
2
ROM2
1
ROM1
0
ROM0
Address
FFF0H Note
After
Reset
R/W
R/W
Internal ROM Size SelectionROM3
60 Kbytes1
ROM2
1
ROM1
1
ROM0
1
Setting prohibitedOther than above
Internal High-Speed RAM Size Selection
RAM2 RAM1 RAM0
Setting prohibitedOther than above
1024 bytes110