Questions and Answers
What is a loader?
A loader is a part of the operating system that loads an executable file into memory and prepares it for execution.
Which of the following is NOT a function of a loader?
Which type of loader directly assembles machine instructions and places them into their assigned memory locations?
An absolute loader requires relocation information during loading.
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What does program relocation do?
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What does a macro processor automate?
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Macros can lead to easier debugging due to their defined sequences.
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What is the major advantage of using macros in programming?
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Which of the following is a disadvantage of using macros?
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A macro is defined using the syntax #define [macro_name]([parameters]) [body] in languages like _____.
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Study Notes
Loaders and Linkers
- A loader is part of the operating system responsible for loading executable files into memory for execution.
- Main functions of loaders include loading, relocation, initialization, and transferring control to programs.
Functions of Loader
- Loading: Reads executable files from disk and places them into memory.
- Relocation: Adjusts program addresses to match actual memory locations assigned during loading.
- Initialization: Sets initial values for stack, registers, and runtime components.
- Transfer Control: Transfers execution to the program by pointing the program counter to the entry point.
Types of Loaders
- Compile and Go Loader: Reads and directly assembles code into memory in a single step. Suitable for early programming languages like FORTRAN.
- General Loader: Converts source to object program and facilitates multiple languages without memory wastage.
- Absolute Loader: Loads pre-relocated object files at specified memory locations, requiring programmer to provide starting addresses.
- Direct Linking Loader: Cannot access source code directly; uses external symbols and requires the assembler to provide necessary object code information.
Loader Types Details
- Direct Linking Loaders: Involves managing length, external symbols, and constants for relocation and linkage during loading.
- Machine-dependent Loader Features: Include program relocation and linking capabilities that depend on machine architecture.
Machine Independent Loader Features
- Automatic Library Search: Handles external references and links subprogram library routines automatically during loading.
- Loader Options: Allows users to modify loading processes, delete external symbols, or rename them.
Macro Processors
- A macro processor automates inserting sequences of code, enhancing efficiency and readability.
- Advantages: Simplifies coding, promotes reusability, enhances readability, and maintains ease of changes across multiple uses.
- Disadvantages: Increase in program size, debugging difficulties, potential for complexity, and namespace pollution issues.
Macro Processor Functions
- Definition and Invocation: Macros defined once can be invoked multiple times with parameters substituted during expansion.
- Conditional Compilation: Can include/exclude code segments based on conditions.
- File Inclusion: Macros facilitate the inclusion of header files in languages like C/C++.
Machine-independent Macro-Processor Features
- Concatenation of Parameters: Allows combining parameters with strings.
- Unique Labels: Generates distinct labels for every macro invocation.
- Keyword Parameters: Matches parameters and arguments according to their specified order in macro definitions.
Macro Processing in Language Translators
- Macro processors function as preprocessors that expand macro invocations before passing the expanded code to assemblers or compilers.
- Line-by-Line Macro Processor: Processes definitions and expands macros before code compilation.
- Integrated Macro Processor: Leverages information from the source program context, supporting more complex macro instructions.
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Description
This quiz covers the essential concepts from Chapter Nine of the Operating Systems course, focusing on loaders and linkers. Key topics include basic loader functions, relocation, and program linking, along with machine-dependent and machine-independent loader features. Test your understanding of the algorithms and data structures related to linking loaders.
