Z8FMC16100 Series Flash MCU
Product Specification
13
Address Space
The eZ8 CPU can access three distinct address spaces:
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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 hold 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 (UM0128), available for download at www.zilog.com.
Register File
The Z8FMC16100 Series Flash MCU supports up to 512B of internal RAM within the
Register File address space. The Register File is composed of two sections—control regis-
ters and general-purpose registers (RAM). When instructions are executed, registers are
read from when defined as sources and written to when defined as destinations. The archi-
tecture 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 4KB 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 F00hto 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 recommended and can produce unpre-
dictable results.
Caution:
The on-chip RAM always begins at address 000hin the Register File address space. The
Z8FMC16100 Series Flash MCU devices provide 512B 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. See the Ordering Information for the
Z8FMC16100 Series Products* section on page 303 to determine the amount of RAM
available for the specific Z8FMC16100 Series Flash MCU device.
PS024604-1005
P R E L I M I N A R Y
Register File
ZILOG [ ZILOG, INC. ]
