Software interruptions can be thoroughly activated by the assembler invoking the number of the preferred interruption with the INT instruction.
The use of interruptions aids us in the creation of programs, and by using those programs are shorter, it is simpler to understand them and they regularly have a better performance more often than not due to their smaller size.
This type of interruptions can be estranged in two categories: the operative system DOS interruptions and the BIOS interruptions.
The dissimilarity between the two is that the operative system interruptions are simpler to use but they are also slower as these interruptions make use of the BIOS to get their goal, on the other hand the BIOS interruptions are much quicker but they have the difficulty that since they are division of the hardware, they are very specific and can vary depending even on the brand of the constructer of the circuit.
The election of the kind of interruption to use will depend solely on the features you want to give your program: speed, using the BIOS ones, or portability, by means of the ones from the DOS.