MC68030RC40C Freescale Semiconductor, MC68030RC40C Datasheet - Page 334

• Manufacturer Part Number: MC68030RC40C
• Description: IC MPU 32BIT ENHANCED 128-PGA
• Manufacturer: Freescale Semiconductor

Specifications of MC68030RC40C

• Processor Type: M680x0 32-Bit
• Speed: 40MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 128-PGA
• Family Name: M68000
• Device Core: ColdFire
• Device Core Size: 32b
• Frequency (max): 40MHz
• 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: 128
• Package Type: PGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Compliant

9.5.3 Variations in Translation Table Structure
9.5.3.1 EARLY TERMINATION AND C O N T I G U O U S MEMORY.
MOTOROLA
the MMU for a particular system. The following paragraphs discuss the var-
the ability to map a contiguous range of the logical address space (an integral
would normally contain a table pointer, thereby deleting a subtree of the
table.
The table search ends when the search encounters a page descriptor, whether
the translation tree.
table (i.e., the MC68030 has not encountered a TIx field of zero) is called an
An early termination page descriptor takes the place of many page descriptors
termination page descriptor is a long format, the limit field is applied to the
able, allowing the system designer flexibility to optimize the performance of
with a single descriptor. This is done by placing the code for page descriptor
($1) in the descriptor type (DT) field of a descriptor at a level of the tree that
or not the page descriptor is in a page descriptor table at the lowest level of
Termination of the table search by a page descriptor in a pointer descriptor
early termination. The terminating page descriptor is called an early termi-
on which the descriptor has been placed, and on any branches from that
scriptors for additional information.
of 2 PS+n bytes.
Many aspects of the MMU translation tree structure are software configur-
iations of the tree structure from the general structure discussed previously.
number of logical pages) to an equivalent contiguous physical address range
nation page descriptor.
in a translation table. It applies to all pages that would exist on the branch
branch. An early termination page descriptor can be used where contiguous
pages in physical memory correspond to contiguous logical pages. If an early
next i n d e x field of the logical address. This allows the number of pages
mapped contiguously to be restricted. Refer to 9.1.2 Translation Table De-
If n low-order bits of the logical page address are unused when a page
descriptor encoding is encountered, the single descriptor creates a mapping
of a contiguous region of the logical address space starting at the logical
page address (with n unused bits set to zero) to a contiguous region in the
physical address space starting at the page frame base address with a size
MC68030 USER'S MANUAL
The MMU provides
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