Zilog Z8F0130 - Manual (Page 32)

eZ8
™
CPU Core
User Manual
UM012820-0810 Address Space
17
Address Space
The eZ8
™
CPU can access three distinct address spaces:
•
The Register File contains addresses for the general-purpose registers
and the eZ8 CPU, peripheral, and I/O port control registers.
•
The Program Memory contains addresses for all memory locations
having executable code and/or data.
•
The Data Memory contains addresses for all memory locations that
hold data only.
Register File
The eZ8 CPU supports a maximum of 4096 consecutive bytes (registers)
in the Register File. The Register File is composed of two sections:
1. Control Registers
2. General-Purpose Registers
The upper 256 bytes are reserved for control of the eZ8 CPU, the on-chip
peripherals, and the I/O ports. These 256 registers are always located at
addresses from
F00h to FFFh .
When instructions execute, registers are read from when defined as
sources and written to when defined as destinations. The architecture of
the eZ8 CPU allows all general-purpose registers to function as
accumulators, address pointers, index registers, stack areas, or scratch pad
memory.
Some eZ8 CPU products contain a register file that is less than the
maximum of 4096 bytes. For eZ8 CPU products with less than 4096B in
the Register File, reading from an unavailable Register File addresses
returns an undefined value. Writing to an unavailable Register File
addresses produces no effect. Refer to the Zilog Product Specification