MC68030FE20C Freescale Semiconductor, MC68030FE20C Datasheet - Page 375

• Manufacturer Part Number: MC68030FE20C
• Description: IC MPU 32BIT ENHANCED 132-CQFP
• Manufacturer: Freescale Semiconductor

Specifications of MC68030FE20C

• Processor Type: M680x0 32-Bit
• Speed: 20MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 132-CQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

9
9-74
The operating system must control memory allocation for physical memory
the kernel, private memory pool) permanently reside in some of the memory.
The operating system maintains a linked list of all unallocated page frames.
to the next frame. The operating system takes the first page frame on the
When all frames are allocated, GetFrame steals a frame from another task.
(page frames) to hold the pages of virtual memory. All available physical
memory. A system with 4 Mbytes of actual memory is divided into 512
8K-byte frames that can theoretically hold 512 pages of active virtual memory
at any one time. Usually, operating system components (exception handlers,
Only the remaining page frames are available for virtual memory pages.
One simple way to do this is for each unallocated frame to contain a pointer
could be stolen without waiting for the page to be copied back to the external
storage device that stores virtual page images. (This device is called the
device, then steals the page frame and returns to the caller with the physical
to allocate and free supervisor work memory. The routine must allocate
a 64K I/O area, and 1 Mbyte of RAM, the physical mapping appears as follows:
memory is divided into page frames, each of which can hold a page of virtual
list when a frame is required. An operating system primitive called GetFrame
performs this function and returns the physical address of an available frame.
GetFrame first looks for an unmodified frame to steal. An unmodified frame
paging device orthe backing store.) If no unmodified page frame is available,
GetFrame must wait while the system copies a modified page to the paging
address.
Next, the operating system needs physical memory management routines
pieces of memory on boundaries of at least modulo 16, the requirement for
In a typical computer system, with 64K bytes of boot and diagnostics ROM,
LOW MEMORY
MC68030 USER'S MANUAL
0,i
3M
1M
2M
BOOT AND OlAGNOSTICS ROM
HARDWAREI/0
SYSTEM RAM
UNMAPPED
i
MOTOROLA