NEC uPD78P078 User Manual
Page 532

532
CHAPTER 23 EXTERNAL DEVICE EXPANSION FUNCTION
1
1
48 Kbytes
56 Kbytes
Note 2
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 1
After
Reset
R/W
R/W
Internal ROM size selection
ROM3
60 Kbytes
1
ROM2
1
ROM1
1
ROM0
0
Setting prohibited
Other than above
Internal high-speed RAM size selection
RAM2 RAM1 RAM0
1024 bytes
1
1
0
Setting prohibited
Other than above
(2) Internal memory size switching register (IMS)
The
µ
PD78P078, 78P078Y can specify the internal memory size by internal memory size switching register
(IMS).
IMS is set with an 8-bit memory manipulation instruction.
RESET input sets this register to the value indicated in Table 23-5.
Figure 23-3. Internal Memory Size Switching Register Format
Notes 1. The values after reset depend on the product. (See Table 23-5)
Table 23-5. Values when the Internal Memory Size Switching Register is Reset
Type Number
Reset Value
µ
PD78076, 78076Y
CCH
µ
PD78078, 78078Y
CFH
µ
PD78P078, 78P078Y
2. When using the external device expansion function in the
µ
PD78078, 78078Y, 78P078, and
78P078Y set the internal ROM size to 56 Kbytes.
Caution When using the mask ROM products, do not set the values other than CCH and CFH to the
IMS except for the cases where the external device extension function is used in
µ
PD78078
and 78078Y.
Remark
IMS should be set according to the internal ROM capacity.