1. What are the basic functions of loaders?
Loading – brings the object program into memory for execution
Relocation – modifies the object program so that it can be loaded at an address different from the location originally specified
Linking – combines two or more separate object programs and also supplies the information needed to reference them.
2. Define absolute loader.
The loader, which is used only for loading, is known as absolute loader. e.g. Bootstrap loader
3. What is meant by bootstrap loader?
This is a special type of absolute loader which loads the first program to be run by the computer. (usually an operating system)
4. What are relative (relocative) loaders?
Loaders that allow for program relocation are called relocating (relocative) loaders.
5. What is the use of modification record?
Modification record is used for program relocation. Each modification record specifies the starting address and the length of the field whose value is to be altered and also describes the modification to be performed.
6. What are the 2 different techniques used for relocation?
Modification record method and Relocation bit method.
7. Define Relocation bit method.
If the relocation bit corresponding to a word of object code is set to 1, the program‟s starting address is to be added to this word when the program is relocated. Bit value 0 indicates no modification is required.
8. Define bit mask.
The relocation bits are gathered together following the length indicator in each text record and which is called as bit mask. For e.g. the bit mask FFC (111111111100) specifies that the first 10 words of object code are to be modified during relocation.
9. What is the need of ESTAB?
It is used to store the name and address of the each external symbol. It also indicates in which control section the symbol is defined.
10. What is the use of the variable PROGADDR?
It gives the beginning address in memory where the linked program is to be loaded. The starting address is obtained from the operating system.
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