MC68030RC20C Freescale Semiconductor, MC68030RC20C Datasheet - Page 341

• Manufacturer Part Number: MC68030RC20C
• Description: IC MPU 32BIT ENHANCED 128-PGA
• Manufacturer: Freescale Semiconductor

Specifications of MC68030RC20C

• Processor Type: M680x0 32-Bit
• Speed: 20MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 128-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: 128
• Package Type: PGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Compliant

9
9.5.3.5 DYNAMIC ALLOCATION OF TABLES.
9.5.4 Detail of Table Search Operations
9-40
the areas of memory that are used by a task over any extended period of
translation tree for a task.
than guessing what the memory usage requirements of the task are, the
the task requests access to the areas mapped by these branches. This tech-
for each task, conserving physical memory utilization and minimizing op-
translation tree can be dynamically allocated by the operating system based
on requests for access to particular areas.
As in the case of demand paging, it is difficult, if not impossible, to predict
time. Instead of attempting to predict the requirements of the task, the op-
erating system performs no action for a task until a demand is made re-
questing access to a previously unused area or an area that is no longer
execute a' previously unexecuted task that has no translation tree. Rather
operating system creates a translation tree for the task that maps one page
corresponding to the initial value of the program counter for that task, and
other branches of the translation tree for this task remain unallocated until
erating system overhead.
The table search operations described in this section are shown in detail in
it is not required that a complete translation tree exist for an active task. The
resident in memory. This same technique can be used to efficiently create a
For example, consider an operating system that is preparing the system to
possibly, one page corresponding to the initial stack pointer of the task. All
nique allows the operating system to construct a minimal translation tree
Figures 9-25-9-29.
MC68030 USER'S MANUAL
Similar to the case of paged tables,
MOTOROLA