
CPU16
REFERENCE MANUAL
SYSTEM RESOURCES
MOTOROLA
3-1
SECTION 3 SYSTEM RESOURCES
This section provides information concerning CPU16 register organization, memory
management, and bus interfacing. The CPU16 is a subcomponent of a modular micro-
controller. Due to the diversity of modular microcontrollers, detailed information con-
cerning interaction with other modules and external devices is contained in the
microcontroller user's manual.
3.1 General
The CPU16 was designed to provide compatibility with the M68HC11 and to provide
additional capabilities associated with 16- and 32-bit data sizes, 20-bit addressing,
and digital signal processing. CPU16 registers are an integral part of the CPU and are
not addressed as memory locations. The CPU16 register model contains all the re-
sources of the M68HC11, plus additional resources.
The CPU16 treats all peripheral, I/O, and memory locations as parts of a pseudolinear
1 Megabyte address space. There are no special instructions for I/O that are separate
from instructions for addressing memory. Address space is made up of 16 64-Kbyte
banks. Specialized bank addressing techniques and support registers provide trans-
parent access across bank boundaries.
The CPU16 interacts with external devices and with other modules within the micro-
controller via a standardized bus and bus interface. There are bus protocols for mem-
ory and peripheral accesses, as well as for managing an hierarchy of interrupt
priorities.
3.2 Register Model
Figure 3-1
following paragraphs.
shows the CPU16 register model. Registers are discussed in detail in the
F
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