Memory Size Switching Register ( Pd78P058); Memory Size Switching Register Format ( Pd78P058); Examples Of Memory Size Switching Register Settings ( Pd78P058) - NEC PD78052 User Manual

26.2 Memory Size Switching Register ( PD78P058)

The PD78P058 allows users to define its internal ROM and high-speed RAM sizes using the memory size
switching register (IMS), so that the same memory mapping as that of a mask ROM version with a different-size internal
ROM and high-speed RAM is possible. IMS is set with an 8-bit memory manipulation instruction.
RESET input sets IMS to CFH.
Figure 26-2. Memory Size Switching Register Format ( PD78P058)
Symbol 7 6 5
IMS RAM2 RAM1 RAM0
The IMS settings to give the same memory map as mask ROM versions are shown in Table 26-4.
Table 26-4. Examples of Memory Size Switching Register Settings ( PD78P058)
550
CHAPTER 26 PD78P054, 78P058
4 3 2 1 0
0 ROM3 ROM2 ROM1 ROM0
Relevant Mask ROM Version
PD78052, 78052Y
PD78053, 78053Y
PD78054, 78054Y
PD78055, 78055Y
PD78056, 78056Y
PD78058, 78058Y
After
Address
Reset
FFF0H CFH
ROM3 ROM2 ROM1 ROM0 Internal ROM Capacity selection
0 1 0 0 16 Kbytes
0 1 1 0 24 Kbytes
1 0 0 0 32 Kbytes
1 0 1 0 40 Kbytes
1 1 0 0 48 Kbytes
1 1 1 0 56 Kbytes
1 1 1
1 60 Kbytes
Other than above Setting prohibited
RAM2 RAM1 RAM0 Internal High-Speed RAM Capacity Selection
0 1 0 512 bytes
1 1 0 1024 bytes
Other than above Setting prohibited
IMS Setting
44H
C6H
C8H
CAH
CCH
CFH
R/W
R/W