CHAPTER 26 FLASH MEMORY
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26.2 Internal Expansion RAM Size Switching Register
The internal expansion RAM capacity can be selected using the internal expansion RAM size switching register
(IXS).
This register is set by an 8-bit memory manipulation instruction.
RESET input sets IXS to 0CH.
Caution The initial value of IXS is 0CH. Be sure to set each product to the values shown in Table 26-3 at
initialization. Also, when using the 78K0/KE1+ to evaluate the program of a mask ROM version
of the 78K0/KE1, be sure to set the values shown in Table 26-3.
Figure 26-2. Format of Internal Expansion RAM Size Switching Register (IXS)
Address: FFF4H After reset: 0CH R/W
Symbol 7 6 5 4 3 2 1 0
IXS
0
0
0
IXRAM4 IXRAM3 IXRAM2 IXRAM1 IXRAM0
IXRAM4
IXRAM3
IXRAM2
IXRAM1
IXRAM0
Internal expansion RAM capacity selection
0 1 1 0 0
0
bytes
0 1 0 1 0
1024
bytes
Other than above
Setting prohibited
The IXS settings required to obtain the same memory map as mask ROM versions of the 78K0/KE1 are shown in
Table 26-3.
Table 26-3. Internal Expansion RAM Size Switching Register Settings
Flash Memory Versions
(78K0/KE1+)
Target Mask ROM Versions
(78K0/KE1)
IXS Setting
−
µ
PD780131 0CH
µ
PD78F0132H
µ
PD780132 0CH
µ
PD78F0133H
µ
PD780133 0CH
µ
PD78F0134H
µ
PD780134 0CH
µ
PD78F0136H
µ
PD780136 0AH
µ
PD78F0138H, 78F0138HD
µ
PD780138
0AH