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31 address binding, dynamic loading
- 1. Storage Management Address binding,Dynamic loading 1
- 2. HOME PREVIOUS TOPIC NEXT PREVIOUS QUESTION PAPERS FOR OS CPP TUTORIALS 9CM402.31 2
- 3. Recap In the lastclass, you have learnt • Recovery from Deadlock 3
- 4. Objectives On completionof this period, you will be able to Know about • Storage management • Address binding • Dynamic loading 4
- 5. Primary Memory • Primarymemory is of two types RAM and ROM • RAM – Random Access Memory – Volatile Memory – Can be directly accessibly by the CPU – Speed of RAM is compatible to Processor speed – Capacity is in GB’s • ROM – Read Only Memory – Non Volatile 5
- 6. Storage Management • Memoryis a large array of words or bytes with its own addresses • In Single user operating system entire memory belongs to a single process Ex. DOS • In multi user operating system many processes share the memory Ex. UNIX, Windows NT, Windows 2003 server etc. 6
- 7. Storage Management What ismeant by storage management? • Allocate memory to multiple processes and prevents them from overlapping • Memory is utilized in an efficient manner 7
- 8. Instruction Execution Cycle •Instruction is fetched from memory • Decoded and may cause operands to be fetched from memory • After executing the instruction on the operands the results are stored back in memory Start Fetch Execute Halt Fig - 1 8
- 9. Multistep Processing ofUser Program Fig - 2 9
- 10. Address Binding • Programmust be brought into memory and placed with in a process for it to be run • Collection of processes on the disk that are waiting to be brought into memory for execution - Input queue • A user program will go through several steps before being executed as shown in Fig - 2 10
- 11. Address Binding • Addressis represented in different ways during this steps • Address in source program is symbolic (Ex. COUNT) • Compiler bind these symbolic addresses to relocatable addresses such as – 14 bytes from the beginning of this module 11
- 12. Address Binding • Relocatablemeans that the program image can reside anywhere in physical memory • A linkage editor or a loader bind relocatable addresses to absolute addresses ( such as 74014 ) • Each binding is a mapping from one address space to another 12
- 13. Address Binding • Bindingof instruction and data to memory address can be done at – Compile time – Load time – Execution time 13
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- 17. Dynamic Loading • Routineis not loaded until it is called • All routines are kept on disk in a relocatable load format • Main program is loaded and executed • A routine needs to call another routine 17
- 18. Dynamic Loading • Therelocatable linking loader is called to load the desired routine • Control is passed to newly loaded routine • Routine is called into memory only when it is needed 18
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- 20. Dynamic Loading -Example Secondary storage routine( ) Memory { • main( ) ------- ; { ------- ; ---- ; ------- ; ---- ; } routine( ); // routine is called dynamically ---- ; } 20
- 21. Dynamic Loading Advantages •Better memory utilization • Unused routine is never loaded • Useful when large amounts of code are needed to handle infrequently occurring cases – Ex. Error routines – Although the total program size may be large, the portion i.e., used is much smaller 21
- 22. Dynamic Loading Advantages • Nospecial support from the operating system is required • Implemented through program design • Operating system provides library routines to implement dynamic loading 22
- 23. Summary In thisclass, you have learnt • Storage Management • Address binding • Dynamic loading • Advantages of dynamic loading 23
- 24. Frequently Asked Questions •What is address binding? • What is meant by Dynamic loading? • Explain the concepts of Dynamic loading • What are the advantages of Dynamic loading? 24
- 25. Quiz 1. Memory isa large array of a) Words b) Registers c) Bits d) None 25
- 26. Quiz 2. Address insource program is address a) Relocatable b) Symbolic c) Absolute d)None 26
- 27. Quiz 3. Compiler bindssymbolic address to _________ address a) Absolute b) Symbolic c) Relocatable d) None 27
- 28. Quiz 4. Loader bindsrelocatable address to ________ address a) Absolute b) Symbolic c) Relocatable d) None 28
- 29. Quiz 5. All routinesare kept on disk in a ______ load format a) Relocatable b) Symbolic c) Absolute d) None 29
- 30. Quiz 6. Special supportfrom the operating system is required a) Yes b) NO 30
- 31. Other subject materials • Web designing • Micro processors • C++ tutorials • java home
- 32. Quiz 7. Routine isnot called until it is required in dynamic loading a) True b) False 32