Advantages of Paging Memory Management

1. No external fragmentation
• Any page can be placed in any frame in physical memory
• Fast to allocate and free

  1. Alloc: No searching for suitable free space.
  2. Free: Doesn’t have to collapse with adjacent free space.
  3. Just use bitmap to show free/allocated page frames

2. Simple to swap-out portions of memory to disk
• Page size matches disk block size
• Can run process when some pages are on disk
• Add “present” bit to PTE
3. Enables sharing of portions of address space
• To share a page, have PTE point to same frame.
Conversion of Logical Address into Physical Address
The IP address is a 32-bit Logical Address, but the Physical Address depends on the hardware.  For example, ARCNET has an 8-bit hardware address, while Ethernet has a 48-bit hardware address.

Address Resolution Protocol (ARP)    
In order for two machines on a given network to communicate, they must know the other machine's physical address (MAC address).  By broadcasting ARPs, a host can dynamically discover the MAC-layer addresses corresponding to a particular IP network-layer address.


Hardware involved in the conversion of logical address into physical address

1. A data processing system for debugging software, the system comprising:

  1. a main memory for receiving logical and physical address data;
  2. a data bus;
  3. a data processor in communication with the main memory through the data bus, said data processor including:

(i) a memory management unit for converting logical address data to physical address data,
(ii) a means for generating an indication signal representing an access of the main memory by the data processor wherein, said indication signal is generated upon detection that selected logical address data is absent from the memory management unit; and an emulator in communication with an address bus, said emulator including:
(i) a means for storing address conversion information from the data bus,
(ii) a means for converting physical address data to logical address data; and

an electrode means for directly transmitting the indication signal from the memory management unit of the data processor to the emulator, the indication signal enabling the emulator to access the physical address data from the address bus and permitting the storage of newly generated address conversion information in the address conversion information storing means for conversion of physical address data to logical address data by the converting means of the emulator