Question

Briefly explain the design of an absolute loader

Answer 1

A loader reads or loads a program from an input device into memory for execution. Generally, computers use punched cards, punched paper tape, magnetic tape, disk or drum for loading. There are different types of loaders. An absolute loader is the simplest type of loader.

The input for an absolute loader is in loader format. The input to the loader consists of two pieces of information:

1. The instruction or data to be loaded.

2. The address where it should be loaded.

There is a end-of-file marker at the end of the loader input to let the loader know that it has to stop. After it stops it has to transfer the control to the newly loaded program. So there is a starting address after that.

Answer 2

An absolute loader is a simple and fast operating loader. The file is loaded by the loader into the memory location that is given at the header or beginning of the file. In other words, the code is placed in the memory location that starts with the initial address specified the assembler. After this, control is passed on to the program for execution. If the loading location specified is not free, the execution process will not take place and will happen only when the specified location is free to load the file.

In an absolute loader, both loading and linking are done by the programmer. So, he/she must take care to ensure that there is no overlapping of programs. Also, he/she must be well informed about the runtime address.