Datasheet

V850ES/JG3 CHAPTER 3 CPU FUNCTION
R01UH0015EJ0300 Rev.3.00 Page 44 of 870
Sep 30, 2010
3.4.5 Recommended use of address space
The architecture of the V850ES/JG3 requires that a register that serves as a pointer be secured for address generation
when operand data in the data space is accessed. The address stored in this pointer ±32 KB can be directly accessed by
an instruction for operand data. Because the number of general-purpose registers that can be used as a pointer is limited,
however, by keeping the performance from dropping during address calculation when a pointer value is changed, as many
general-purpose registers as possible can be secured for variables, and the program size can be reduced.
(1) Program space
Of the 32 bits of the PC (program counter), the higher 6 bits are fixed to 0, and only the lower 26 bits are valid.
Regarding the program space, therefore, a 64 MB space of contiguous addresses starting from 00000000H
unconditionally corresponds to the memory map.
To use the internal RAM area as the program space, access addresses 03FF0000H to 03FFEFFFH.
Caution If a branch instruction is at the upper limit of the internal RAM area, a prefetch operation (invalid
fetch) straddling the on-chip peripheral I/O area does not occur.
(2) Data space
With the V850ES/JG3, it seems that there are sixty-four 64 MB address spaces on the 4 GB CPU address space.
Therefore, the least significant bit (bit 25) of a 26-bit address is sign-extended to 32 bits and allocated as an
address.