MC68030 Datasheet, PDF (427/602 Pages) Motorola, Inc – ENHANCED 32-BIT MICROPROCESSOR

Coprocessor Interface Description
Primitive
Protocol
Transfer Status and/or ScanPC
X
Protocol: If Used with Conditional Instruction
Other:
1. Trace — Trace Made Pending if MC68020 in ``Trace on Change
of Flow'' Mode and DR=1
2. Address Error — If Odd value Written to ScanPC
Take Pre-Instruction, Mid-Instruction, or Post-Instruction Exception
X
Exception Depends on Vector Supplies in Primitive
F-Line
X
*Use of this primitive with CA=0 will cause protocol violation on conditional instructions.
Abbreviations:
EA=Effective Address
CP=Coprocessor
Other
X
X
When the MC68030 detects a protocol violation, it does not automatically notify the
coprocessor of the resulting exception by writing to the control CIR. The exception handling
routine may, however, use the MOVES instruction to read the response CIR and thus
determine the primitive that caused the MC68030 to initiate protocol violation exception
processing. The main processor initiates exception processing using the mid-instruction
stack frame (refer to Figure 10-43) and the coprocessor protocol violation exception vector
number 13. If the exception handler does not modify the stack frame, the main processor
reads the response CIR again following the execution of an RTE instruction to return from
the exception handler. This protocol allows extensions to the M68000 coprocessor interface
to be emulated in software by a main processor that does not provide hardware support for
these extensions. Thus, the protocol violation is transparent to the coprocessor if the
primitive execution can be emulated in software by the main processor.
MOTOROLA
MC68030 USER’S MANUAL
10-67