Loading & Linking

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An AI-generated summary of this video lecture.

This lecture introduces the operating system concepts of loading and linking, using a slide-based presentation and a C-language example. The instructor first defines loading as the process of bringing a program from secondary storage into main memory (RAM) for execution. Two types of loading are compared: static loading, where the entire program is loaded before execution, resulting in faster execution but inefficient memory utilization; and dynamic loading, where routines are loaded on demand, which improves memory utilization but adds additional time. Diagrams show a “Program on Disk” containing Routine A, B, C, and D moving into “Main Memory (RAM)”; in the dynamic case, only some routines are shown loaded. The lesson then transitions to linking, defined as the process of combining different modules or functions of a program to create an executable program. A C example uses File 1: main.c with a function declaration int add(int, int); and File 2: add.c with the definition int add(int a, int b) { return a + b; }. A flow diagram shows compilation producing object files main.o and add.o, a linker combining them into an executable file (a.out / program.exe), execution, and an output of 30. The final section covers types of linking: static linking, which combines all required modules and library functions into a single executable file, making it generally larger; and dynamic linking, which connects to library functions at load time or runtime, allowing libraries to be shared by multiple programs and resulting in a smaller executable file.

Chapters

1. 0:00 – 2:00 00:00-02:00

   The instructor introduces the topic “Loading” with the heading “Types of Loading.” The slide defines loading as “the process of bringing a program from secondary storage into main memory (RAM) for execution.” Two panels compare “1 Static Loading” and “2 Dynamic Loading.” Diagrams show a “Program on Disk” box listing Routine A, B, C, and D with an arrow to a “Main Memory (RAM)” box. Red-highlighted terms include “entire program,” “inefficient utilization of memory,” “faster,” “on demand,” “improves memory utilization,” and “additional time.”

2. 2:00 – 5:00 02:00-05:00

   The instructor explains the two loading types in more detail. Static loading brings the entire program into memory before execution, which is faster but leads to inefficient memory utilization. Dynamic loading loads routines on demand, improving memory utilization but requiring additional time. The instructor points to the static diagram and then to the dynamic “Main Memory (RAM)” box, which shows only Routine A and B loaded. A C code example is written on the whiteboard to illustrate function calls, connecting the loading discussion to the upcoming linking example.

3. 5:00 – 10:00 05:00-10:00

   The lesson transitions from loading to linking. The slide states that “Linking is the process of combining different modules or functions of a program to create an executable program.” An “Example of Linking in C” shows two code panels: “File 1 : main.c” containing “int add(int, int); // function declaration” and “File 2 : add.c” containing “int add(int a, int b)” and “return a + b;.” A right-hand panel titled “How Linking Works?” lists five numbered steps, ending with “A single executable file is created.”

4. 10:00 – 15:00 10:00-15:00

   The instructor walks through the linking flow diagram. Pink “Compilation (Compiler)” boxes feed “main.o (Object File)” and “add.o (Object File).” A “Linker” box combines these into an “Executable File (a.out / program.exe),” which leads to “Execution” and a circled “Output 30.” The slide then switches to “Types of Linking,” divided into “1 Static Linking” and “2 Dynamic Linking” columns, each with its own module-to-executable diagram. The instructor uses a pen to circle the executable box in the static diagram.

5. 15:00 – 18:39 15:00-18:39

   The instructor compares static and dynamic linking. Static linking combines “all required modules” and “library functions” into a single executable file, making it generally larger. Dynamic linking connects to library functions at “load time or runtime,” allowing them to be “shared by multiple programs” and resulting in a smaller executable file. The instructor highlights these key terms and draws diagrams showing modules and library code being combined by a linker, and Program A and Program B using a dynamic linker to access a shared library.

The lecture progresses logically from loading to linking, two fundamental steps in preparing a program for execution. Loading is defined as moving a program from secondary storage into RAM. Static loading loads the entire program upfront, trading memory efficiency for speed, while dynamic loading loads routines on demand, improving memory utilization at the cost of additional time. The C example with main.c and add.c bridges loading and linking by showing how separate source files are compiled into object files and then linked into a single executable. The linking flow diagram—compilation, object files, linker, executable, execution, output 30—makes the process concrete. Finally, static and dynamic linking are contrasted: static linking embeds all needed code into the executable, increasing its size, while dynamic linking uses shared libraries at load or runtime, reducing executable size and enabling code sharing. The recurring theme is the trade-off between memory/disk efficiency and execution speed, illustrated through consistent diagrams and a single C example.