Wraparound Of Cpu Address Space - NEC V850ES/KE1+ User Manual

3.4.2 Wraparound of CPU address space

(1) Program space
Of the 32 bits of the program counter (PC), the higher 6 bits are fixed to 0 and only the lower 26 bits are valid.
Even if a carry or borrow occurs from bit 25 to bit 26 as a result of branch address calculation, the higher 6 bits
ignore this and remain 0.
Therefore, the lower-limit address of the program space, 00000000H, and the upper-limit address,
03FFFFFFH, are contiguous addresses, and the program space is wrapped around at the boundary of these
addresses.
Caution No instructions can be fetched from the 4 KB area of 03FFF000H to 03FFFFFFH because this
area is an on-chip peripheral I/O area. Therefore, do not execute any branch operation
instructions in which the destination address will reside in any part of this area.
00000001H
00000000H
03FFFFFFH
03FFFFFEH
(2) Data space
The result of an operand address calculation that exceeds 32 bits is ignored.
Therefore, the lower-limit address of the data space, address 00000000H, and the upper-limit address,
FFFFFFFFH, are contiguous addresses, and the data space is wrapped around at the boundary of these
addresses.
00000001H
00000000H
FFFFFFFFH
FFFFFFFEH
CHAPTER 3 CPU FUNCTIONS
Program space
(+) direction
Program space
Data space
(+) direction
Data space
User's Manual U16896EJ2V0UD
(–) direction
(–) direction
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