UM012811-0904
Addressing
Modes
eZ8 CPU
User Manual
22
Figure 9. Register Addressing Using 8-Bit Addresses
Register Addressing Using 4-Bit Addresses
Working Registers or Working Register Pairs may be accessed using 4-bit addresses sup-
plied in the operands. With 4-bit Addressing, the destination and/or source addresses point
to one of the 16 possible Working Registers within the current Working Register Group.
This 4-bit address is combined with the Page Pointer, RP[3:0], and the Working Group
Pointer, RP[7:4], to form the actual 12-bit address in the Register File. The full 12-bit
address is given by {RP[3:0], RP[7:4], Address[3:0]}. Figure 10 illustrates 4-bit address-
ing of the Register File.
One 8-bit
Program Memory
Address
(dst)
One Operand
Instruction
(Example)
Opcode
dst[7:0]
Destination
Register File
Register
12-bit address is
{RP[3:0], dst[7:0]}
