MC68020RC20E Freescale Semiconductor, MC68020RC20E Datasheet - Page 26

• Manufacturer Part Number: MC68020RC20E
• Description: IC MICROPROCESSOR 32BIT 114-PGA
• Manufacturer: Freescale Semiconductor

Specifications of MC68020RC20E

• Processor Type: M680x0 32-Bit
• Speed: 20MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 114-PGA
• Family Name: M68000
• Device Core: ColdFire
• Device Core Size: 32b
• Frequency (max): 20MHz
• Instruction Set Architecture: RISC
• Supply Voltage 1 (typ): 5V
• Operating Supply Voltage (max): 5.25V
• Operating Supply Voltage (min): 4.75V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Through Hole
• Pin Count: 114
• Package Type: PGA
• Lead Free Status / RoHS Status: Contains lead / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Compliant

Freescale Semiconductor, Inc.
1.4 INSTRUCTION SET OVERVIEW
For detailed information on the MC68020/EC020 instruction set, refer to M68000PM/AD,
M68000 Family Programmer’s Reference Manual .
The instructions in the MC68020/EC020 instruction set are listed in Table 1-2. The
instruction set has been tailored to support structured high-level languages and
sophisticated operating systems. Many instructions operate on bytes, words, or long
words, and most instructions can use any of the 18 addressing modes.
1.5 VIRTUAL MEMORY AND VIRTUAL MACHINE CONCEPTS
The full addressing range of the MC68020 is 4 Gbytes (4,294,967,296 bytes) in each of
eight address spaces; the full addressing range of the MC68EC020 is 16 Mbytes
(16,777,216 bytes) in each of the eight address spaces. Even though most systems
implement a smaller physical memory, the system can be made to appear to have a full 4
Gbytes (MC68020) or 16 Mbytes (MC68EC020) of memory available to each user
program by using virtual memory techniques.
In a virtual memory system, a user program can be written as if it has a large amount of
memory available, although the physical memory actually present is much smaller.
Similarly, a system can be designed to allow user programs to access devices that are not
physically present in the system, such as tape drives, disk drives, printers, terminals, and
so forth. With proper software emulation, a physical system can appear to be any other
M68000 computer system to a user program, and the program can be given full access to
all of the resources of that emulated system. Such an emulated system is called a virtual
machine.
1.5.1 Virtual Memory
A system that supports virtual memory has a limited amount of high-speed physical
memory that can be accessed directly by the processor and maintains an image of a
much larger virtual memory on a secondary storage device such as a large-capacity disk
drive. When the processor attempts to access a location in the virtual memory map that is
not resident in physical memory, a page fault occurs. The access to that location is
temporarily suspended while the necessary data is fetched from secondary storage and
placed in physical memory. The suspended access is then either restarted or continued.
The MC68020/EC020 uses instruction continuation to support virtual memory. When a
bus cycle is terminated with a bus error, the microprocessor suspends the current
instruction and executes the virtual memory bus error handler. When the bus error handler
has completed execution, it returns control to the program that was executing when the
error was detected, reruns the faulted bus cycle (when required), and continues the
suspended instruction.
1-10
M68020 USER’S MANUAL
MOTOROLA
For More Information On This Product,
Go to: www.freescale.com