Z8F4822AR020SG Datasheet, PDF (38/323 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F64xx Series
Product Specification
18
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 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 consists of the addresses for all memory locations that hold only data
These three address spaces are covered briefly in the following sections. For more infor-
mation about the 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! XP F64xx Series is 4 KB (4096 bytes).
The Register File is composed of two sections: control registers and general-purpose reg-
isters. When instructions are executed, 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.
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-byte control register
section are reserved (unavailable). Reading from an reserved Register File addresses
returns an undefined value. Writing to reserved Register File addresses is not recom-
mended and can produce unpredictable results.
The on-chip RAM always begins at address 000H in the Register File address space. The
Z8 Encore! XP F64xx Series provide 2 KB to 4 KB of on-chip RAM depending upon the
device. Reading from Register File addresses outside the available RAM addresses (and
not within the control register address space) returns an undefined value. Writing to these
Register File addresses produces no effect. To determine the amount of RAM available for
the specific Z8 Encore! XP F64xx Series device, see the Part Selection Guide section on
page 2.
PS019924-0113
PRELIMINARY
Address Space