MC68030 Datasheet, PDF (498/602 Pages) Motorola, Inc – ENHANCED 32-BIT MICROPROCESSOR

SECTION 12
APPLICATIONS INFORMATION
This section provides guidelines for using the MC68030. First, it discusses the requirements
for adapting the MC68030 to MC68020 designs. Then, it describes the use of the MC68881
and MC68882 coprocessors with the MC68030. The byte select logic is described next,
followed by memory interface information. A description of external caches, the use of the
STATUS and REFILL signals, and power and ground considerations complete the section.
12.1 ADAPTING THE MC68030 TO MC68020 DESIGNS
Perhaps the easiest way to first utilize the MC68030 is in a system designed for the
MC68020. This is possible due to the complete compatibility of the asynchronous buses of
the MC68020 and MC68030. This section describes how to configure an adapter for the
MC68030 to allow insertion into an existing MC68020-based system. Software and
architectural differences between the two processors are also discussed. The need for an
adapter is absolute because the MC68020 and MC68030 are NOT pin compatible. Use of
the adapter board provides the immediate capability for evaluating the programmer's model
and instruction set of the MC68030 and for developing software to utilize the MC68030's
additional enhanced features. This adapter board also provides a relatively simple method
for increasing the performance of an existing MC68020 or MC68020/MC68851 system by
insertion of a more advanced 32-bit MPU with an on-chip data cache and an on-chip MMU.
Since the adapter board does not support of the synchronous bus interface of the MC68030,
performance measurements for the MC68030 used in this manner may be misleading when
compared to a system designed specifically for the MC68030.
The adapter board plugs into the CPU socket of an MC68020 target system, drawing power,
ground, and clock signals through the socket and running bus cycles in a fashion compatible
with the MC68030. The only support hardware necessary is a single 1K-ohm pullup resistor
and two capacitors for decoupling power and ground on the adapter board.
MOTOROLA
MC68030 USER’S MANUAL
12-1