Z8F082ASH020SC Datasheet, PDF (30/244 Pages) Zilog, Inc. – Z8 Encore XP-R F08xA Series with eXtended Peripherals

Z8 Encore! XP^® F08xA Series
Product Specification
12
Address Space
Overview
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 general-purpose 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 contain data only.
These three address spaces are covered briefly in the following subsections. For more
detailed information regarding the eZ8 CPU and its address space, refer to the eZ8 CPU
User Manual available for download at www.zilog.com.
Register File
The Register File address space in the Z8 Encore!^® MCU is 8KB (8192 bytes). The Regis-
ter File is composed of two sections: control registers and general-purpose registers. When
instructions are executed, registers defined as sources are read, and registers defined as
destinations are written. The architecture of the eZ8 CPU allows all general-purpose regis-
ters to function as accumulators, address pointers, index registers, stack areas, or scratch
pad memory.
The upper 256 bytes of the 8KB Register File address space are reserved for control of the
eZ8 CPU, the on-chip peripherals, and the I/O ports. These registers are located at
addresses from F00H to FFFH. Some of the addresses within the 256B control register sec-
tion are reserved (unavailable). Reading from a reserved Register File address returns an
undefined value. Writing to reserved Register File addresses is not recommended and can
produce unpredictable results.
The on-chip RAM always begins at address 000H in the Register File address space. The
Z8 Encore! XP^® F08xA Series devices contain 1KB of on-chip RAM. Reading from Reg-
ister File addresses outside the available RAM addresses (and not within the control regis-
ter address space) returns an undefined value. Writing to these Register File addresses
produces no effect.
PS024705-0405
PRELIMINARY
Address Space