MC68030 Datasheet, PDF (407/602 Pages) Motorola, Inc – ENHANCED 32-BIT MICROPROCESSOR

Coprocessor Interface Description
Operands longer than four bytes are transferred in increments of four bytes (operand parts)
when possible. The main processor reads a long-word operand part from the operand CIR
and transfers this part to the current effective address. The transfers continue in this manner
using ascending memory locations until all of the long-word operand parts are transferred,
and any remaining operand part is then transferred using a one-, two-, or three-byte transfer
as required. The operand parts are stored in memory using ascending addresses beginning
with the address in the MC68030 temporary register.
The execution of this primitive does not modify any of the registers in the MC68030
programmer's model, even if the previously evaluated effective address mode is the
predecrement or postincrement mode. If the previously evaluated effective addressing
mode used any of the MC68030 internal address or data registers, the effective address
value used is the final value from the preceding primitive. That is, this primitive uses the
value from an evaluate and transfer effective address, evaluate effective address and
transfer data, or transfer multiple coprocessor registers primitive without modification.
The take address and transfer data primitive described in the next section does not replace
the effective address value that has been calculated by the MC68030. The address that the
main processor obtains in response to the take address and transfer data primitive is not
available to the write to previously evaluated effective address primitive.
A coprocessor can issue an evaluate effective address and transfer data primitive followed
by this primitive to perform a read-modify-write operation that is not indivisible. The bus
cycles for this operation are normal bus cycles that can be interrupted, and the bus can be
arbitrated between the cycles.
MOTOROLA
MC68030 USER’S MANUAL
10-47