CHAPTER 3 CPU
Preliminary User’s Manual A14874EJ3V0UM
62
3.4 Areas
3.4.1 ROM area
If a high level is input to the IFIROME pin, the area of ROM that can be accessed when ROM is connected to VFB
is set.
(1) ROM relocation function
A 1 MB area at addresses 00000000H to 000FFFFFH or addresses 00100000H to 001FFFFFH is reserved as
the ROM area.
The area where it is to be located is selected according to the input level to the IFIROB2 pin.
(2) Interrupt/exception table
The NU85E increases the interrupt response speed by assigning fixed jump destination addresses
corresponding to interrupts or exceptions.
This set of jump destination addresses is called the interrupt/exception table and is located at address
00000000H and following. When an interrupt/exception request is acknowledged, processing jumps to the jump
destination address and the program that is written in memory beginning at that address is executed.
Remark
When address 00000000H is set in the external memory area, prepare the jump destination address
for jumping to the reset routine at address 00000000H of the external memory.
Figure 3-9. ROM Area
(a) When IFIROB2 = low level
00000000H
000FFFFFH
00100000H
Interrupt/exception
table
ROM area
External memory area
(b) When IFIROB2 = high level
00000000H
000FFFFFH
00100000H
Interrupt/exception
table
001FFFFFH
00200000H
External memory area
ROM area
External memory area
