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Unformatted text preview: 8 C H A P T E R Memory Management Practice Exercises 8.1 Name two differences between logical and physical addresses. Answer: A logical address does not refer to an actual existing address; rather, it refers to an abstract address in an abstract address space. Con- trast this with a physical address that refers to an actual physical address in memory. A logical address is generated by the CPU and is translated into a physical address by the memory management unit(MMU). There- fore, physical addresses are generated by the MMU. 8.2 Consider a system in which a program can be separated into two parts: code and data. The CPU knows whether it wants an instruction (in- struction fetch) or data (data fetch or store). Therefore, two base–limit register pairs are provided: one for instructions and one for data. The instruction base–limit register pair is automatically read-only, so pro- grams can be shared among different users. Discuss the advantages and disadvantages of this scheme. Answer: The major advantage of this scheme is that it is an effective mechanism for code and data sharing. For example, only one copy of an editor or a compiler needs to be kept in memory, and this code can be shared by all processes needing access to the editor or compiler code....
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This note was uploaded on 11/03/2009 for the course IT OS taught by Professor Dr.stephan during the Winter '09 term at Abu Dhabi University.
- Winter '09
- Operating Systems