Page 119 - DCAP507_SYSTEM_SOFTWARE

Unit 8: Introduction to Linking and Loading

linking is manually solved by the programmer itself by taking care of the mutually dependant Notes
dresses. As you can observe that the control is suitably transferred to the address 5000 for
invoking the other segment, and after that at line number 20 the JMP instruction transfers the
control to the location 2000, essentially at location 2000 the instruction STORE of line number 16
is present. So, resolution of mutual references and linking is done by the programmer.

Notes The task of assembler is to generate the object codes for the above segments and
along with the information like starting address of the memory where in fact the object
code can be positioned at the time of execution. The absolute loader accepts these object
modules from assembler and by reading the information regarding their starting addresses,
it will in fact place (load) them in the memory at mentioned addresses.

The whole process is modeled in the following figure.

Figure 8.3: Process of Absolute Loading

Thus, the absolute loader is simple to execute in this scheme:
1. Allocation is performed by either programmer or assembler
2. Linking is performed by the programmer or assembler
3. Resolution is performed by assembler
4. Simply loading is performed by the loader.
As the name recommends, no relocation information is required, if at all it is necessary then that
task can be completed by either a programmer or assembler.

Advantages

1. It is easy to implement.
2. This scheme permits multiple programs or the source programs written dissimilar
languages. If there are various programs written in dissimilar languages then the respective

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