Z8F082ASJ020EG Datasheet, PDF (32/282 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F082A Series
Product Specification
15
Address Space
The eZ8 CPU can access the following 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
information about eZ8 CPU and its address space, refer to the eZ8 CPU Core User Manual
(UM0128), which is available for download on www.zilog.com.
Register File
The Register File address space in the Z8 Encore! MCU is 4 KB (4096 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 4 KB 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 256 B control register
section 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^™ F082A Series devices contain 256 B to 1 KB of on-chip RAM. Reading
from Register File addresses outside the available RAM addresses (and not within the con-
trol register address space) returns an undefined value. Writing to these Register File
addresses produces no effect.
Program Memory
The eZ8 CPU supports 64 KB of Program Memory address space. The Z8 Encore! XP
F082A Series devices contain 1 KB to 8 KB of on-chip Flash memory in the Program
Memory address space, depending on the device. Reading from Program Memory
PS022827-1212
PRELIMINARY
Address Space