Panasonic MN103S User Manual page 54

Chapter 2
CPU Basics
Data Register (32-bit x 4)
This register can be used generally for all operations. Operations are performed with a 32-bit length and the data
size is converted when sending data to and from the memory or by executing of the EXTB or EXTH instructions.
When loading data, 8-bit data is zero-extended to 32 bits and send to the register. When storing data, the lower 8
bits of the register are sent to the memory. When handling the loaded 8-bit data as a signed integer, the data is
sign-extended from 8 bits to 32 bits with the EXTB instruction. When loading data, 16-bit data is zero-extended to
32 bits and sent to the register. When storing data, the lower 16 bits of the register are sent to the memory. When
handling the loaded 16 bits data as a signed integer, the data is sign-extended from 16 bits to 32 bits with the
EXYH instruction.
Address Register (32-bit x 4)
This register is used as an address pointer, and only instructions (addition, subtraction, and comparison) for
address calculation are supported.
Stack Pointer (32-bit x 4)
This pointer designates the first address of the stack region.
Program Counter (32-bit x 1)
This counter designates the address of the instruction being executed.
Multiply/Divide Register (32-bit x 1)
This register is provided for multiply and divide instructions. It holds the upper 32 bits of 64-bit multiplication
results for multiply instructions and the remainder (32 bits) for divide instructions. Also, the upper 32 bits of the
dividend are loaded to this register before executing divide instructions.
Loop Instruction Register (32-bit x 1)
This register is provided for branch instruction (Lcc), and is used for storing the branch target instruction with
SETLB instruction.
Loop Address Register (32-bit x 1)
This register is provided for branch instruction (Lcc), and is used for storing the fetch address with SETLB
instruction.
II - 6 Programming Model