Zilog Z16F2810 - Manual (Page 34)

Address Space UM018809-0611
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ZNEO
®
CPU Core
User Manual
The ZNEO CPU assembler provides a configurable address range mnemonic (RAM) that
can be specified to locate data and (possibly) program elements in the RAM space
accessed using 16-bit addressing. For more details about data space and segment defini-
tions, refer to the assembler documentation.
I/O Memory
ZNEO CPU supports 8 KB (8,192 bytes) of internal I/O Memory space located at
addresses
FF_E000H through FF_FFFFH (in the 24-bit address space). The I/O Memory
addresses are reserved for control of the ZNEO CPU, the on-chip peripherals, and the I/O
ports.
For descriptions of the peripheral and I/O control registers, refer to the ZNEO product
specification that is specific to your device . Attempts to read from unavailable I/O Mem-
ory addresses return
FFH . Attempts to write to unavailable I/O Memory addresses produce
no effect.
The ZNEO CPU assembler provides a configurable address range mnemonic, IODATA,
that can be specified to locate an address in the reserved I/O Memory space or (if present)
external I/O configured in the adjacent 16-bit addressable memory space. For more details
about data space and segment definitions, refer to the assembler documentation.
I/O Memory Precautions
Some control registers within the I/O Memory provide read-only or write-only access.
When accessing these read-only or write-only registers, ensure that the instructions do not
attempt to read from a write-only register or, conversely, write to a read-only register.
External Memory
ZNEO CPU products support external data and address buses for connecting to additional
external memories and/or memory-mapped peripherals. The external addresses can be
used for storing program code, data, constants, stack, etc. The results of reading from or
writing to unavailable external addresses are undefined.
The ZNEO CPU assembler’s EROM and ERAM address range mnemonics can be config-
ured to include external memory configured in 32-bit addressed memory. These mnemon-
ics can be used to locate data and program elements in nonvolatile or RAM memory, as
required. For more information about data space and segment definitions, refer to the
assembler documentation.
Note: