SECTION 5 CENTRAL PROCESSING UNIT
The CPU32, the instruction processing module of the M68300 family, is based on the
industry-standard MC68000 processor. It has many features of the MC68010 and
MC68020, as well as unique features suited for high-performance controller applica-
tions. This section is an overview of the CPU32. For detailed information concerning
CPU operation, refer to the
CPU32 Reference Manual
(CPU32RM/AD).
5.1 General
Ease of programming is an important consideration in using a microcontroller. The
CPU32 instruction format reflects a philosophy emphasizing register-memory interac-
tion. There are eight multifunction data registers and seven general-purpose address-
ing registers.
All data resources are available to all operations requiring those resources. The data
registers readily support 8-bit (byte), 16-bit (word), and 32-bit (long-word) operand
lengths for all operations. Word and long-word operations support address manipula-
tion. Although the program counter (PC) and stack pointers (SP) are special-purpose
registers, they are also available for most data addressing activities. Ease of program
checking and diagnosis is further enhanced by trace and trap capabilities at the in-
struction level.
A block diagram of the CPU32 is shown in
The major blocks operate in a
highly independent fashion that maximizes concurrence of operation while managing
the essential synchronization of instruction execution and bus operation. The bus con-
troller loads instructions from the data bus into the decode unit. The sequencer and
control unit provide overall chip control, managing the internal buses, registers, and
functions of the execution unit.
5
MC68331
USER’S MANUAL
CENTRAL PROCESSING UNIT
MOTOROLA
5-1
MOTOROLA [ MOTOROLA, INC ]
