MC68HC000RC8 Freescale Semiconductor, MC68HC000RC8 Datasheet - Page 86

• Manufacturer Part Number: MC68HC000RC8
• Description: IC MPU 32BIT 8MHZ 68-PGA
• Manufacturer: Freescale Semiconductor

Specifications of MC68HC000RC8

• Processor Type: M680x0 32-Bit
• Speed: 8MHz
• Voltage: 3.3V, 5V
• Mounting Type: Surface Mount
• Package / Case: 68-PGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

Freescale Semiconductor, Inc.
SECTION 6
EXCEPTION PROCESSING
This section describes operations of the processor outside the normal processing
associated with the execution of instructions. The functions of the bits in the supervisor
portion of the status register are described: the supervisor/user bit, the trace enable bit,
and the interrupt priority mask. Finally, the sequence of memory references and actions
taken by the processor for exception conditions are described in detail.
The processor is always in one of three processing states: normal, exception, or halted.
The normal processing state is associated with instruction execution; the memory
references are to fetch instructions and operands and to store results. A special case of
the normal state is the stopped state, resulting from execution of a STOP instruction. In
this state, no further memory references are made.
An additional, special case of the normal state is the loop mode of the MC68010,
optionally entered when a test condition, decrement, and branch (DBcc) instruction is
executed. In the loop mode, only operand fetches occur. See Appendix A MC68010
Loop Mode Operation.
The exception processing state is associated with interrupts, trap instructions, tracing, and
other exceptional conditions. The exception may be internally generated by an instruction
or by an unusual condition arising during the execution of an instruction. Externally,
exception processing can be forced by an interrupt, by a bus error, or by a reset.
Exception processing provides an efficient context switch so that the processor can
handle unusual conditions.
The halted processing state is an indication of catastrophic hardware failure. For example,
if during the exception processing of a bus error another bus error occurs, the processor
assumes the system is unusable and halts. Only an external reset can restart a halted
processor. Note that a processor in the stopped state is not in the halted state, nor vice
versa.
6.1 PRIVILEGE MODES
The processor operates in one of two levels of privilege: the supervisor mode or the user
mode. The privilege mode determines which operations are legal. The mode is optionally
used by an external memory management device to control and translate accesses. The
mode is also used to choose between the supervisor stack pointer (SSP) and the user
stack pointer (USP) in instruction references.
MOTOROLA
M68000 8-/16-/32-BIT MICROPROCESSORS USER’S MANUAL
6- 1
For More Information On This Product,
Go to: www.freescale.com