MC68EC040RC40A Freescale Semiconductor, MC68EC040RC40A Datasheet - Page 25

• Manufacturer Part Number: MC68EC040RC40A
• Description: IC MPU 32BIT 40MHZ 179-PGA
• Manufacturer: Freescale Semiconductor

Specifications of MC68EC040RC40A

• Processor Type: M680x0 32-Bit
• Speed: 40MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 179-PGA
• Lead Free Status / RoHS Status: Contains lead / RoHS Compliant
• Features: -

more common case of the branch taken, and both execution paths of the branch are
fetched and decoded to minimize refilling of the instruction pipeline.
To improve memory management, the M68040 includes separate, independent paged
MMUs for instruction and data accesses. Each MMU stores recently used address
mappings in separate 64-entry address translation caches (ATCs). Each MMU also has
two transparent translation registers that define a one-to-one mapping for address space
segments ranging in size from 16 Mbytes to 4 Gbytes each.
Two memory units independently interface with the IU and FPU. Each unit consists of an
MMU, an ATC, a main cache, and a snoop controller. The MMUs perform memory
management on a demand-page basis. By translating logical-to-physical addresses using
translation tables stored in memory, the MMUs support virtual memory systems. Each
MMU stores recently used address mappings in an ATC, reducing the average translation
time.
Separate on-chip instruction and data caches operate independently and are accessed in
parallel with address translation. The caches improve the overall performance of the
system by reducing the number of bus transfers required by the processor to fetch
information from memory and by increasing the bus bandwidth available for alternate bus
1-4
FLOATING-
CONVERT
EXECUTE
WRITE-
POINT
BACK
UNIT
INSTRUCTION
CALCULATE
EXECUTE
DECODE
INTEGER
WRITE-
FETCH
FETCH
BACK
UNIT
EA
EA
Freescale Semiconductor, Inc.
For More Information On This Product,
Figure 1-1. Block Diagram
M68040 USER’S MANUAL
Go to: www.freescale.com
INSTRUCTION
DATA
ATC
INSTRUCTION MEMORY UNIT
ATC
OPERAND DATA BUS
MMU/CACHE/SNOOP
MMU/CACHE/SNOOP
DATA MEMORY UNIT
INSTRUCTION
CONTROLLER
CONTROLLER
DATA
INSTRUCTION DATA BUS
INSTRUCTION
CACHE
CACHE
DATA
INSTRUCTION
ADDRESS
ADDRESS
DATA
U
C
O
N
R
O
R
B
S
T
L
L
E
MOTOROLA
ADDRESS
CONTROL
SIGNALS
DATA
BUS
BUS
BUS