It doesnt do you all that much good there, though.
to be able to run a program, you must first download and install it.
Once the software is saved on your hard drive, you could run it.
This is the job of a loader.
A loader is a component of the operating system.
It is essential to starting any utility as it loads the program into memory and prepares it for execution.
The loader is always kept in memory so programs can be loaded as quickly as possible.
It is necessary to load the operating system into system memory to boot up.
This is the task of a specific pop in of loader called the boot loader.
Embedded systems may not necessarily use a loader.
The essential advantage here is that this allows the operating system to page some memory out of physical RAM.
Instead, it stores it on the hard drive.
Paging is typically only done when the computer is running out of RAM.
This is useful because it allows a computer to use more RAM than it has.
Without this process, at least one program would crash as it couldnt store the needed data.
With this, however, the loader can pull a bit of a trick.
This would allow the program to appear loaded instantly, though its not done.
The program is not ready to use now, even though it could look like it.
Another reason is that, typically, when a program is opened, the system has sufficient RAM.
Most people dont keep their computer running at 99% RAM usage constantly.
Responsibilities of a Loader
A loaders precise steps depend on the operating system in question.
A basic UNIX loader has five main functions.
The first is to perform validation checks.
This involves enough physical memory available and the necessary permissions.
Next, the loader actually memory maps the data.
Typically this is done by transferring the data to the main memory.
As mentioned above, the memory could theoretically be mapped to the drive location in a pinch.
Applications can be run with command-line arguments.
These are optional flags that indicate certain behaviors or features that arent enabled by default.
The -h flag is often used to print a text-based help file rather than spin up the program.
These arguments also need to be loaded into memory.
The registers need to be initialized, such as the stack pointer.
Finally, the loader jumps to the first instruction of the program to get it running.
Conclusion
A loader is part of an operating system.
It is responsible for loading applications starting from storage to main memory.
Its responsibilities also extend to beginning the program running.
This means it needs to initialize registers and call the first instruction of the program.
It is known as a boot loader when the loader is responsible for loading the operating system itself.
