tailieunhanh - Cracker Handbook 1.0 part 60

Tham khảo tài liệu 'cracker handbook part 60', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | have to write a program which reads the actual value of the counter and to translates it into an understandable format for the user. External hardware interruptions External interruptions are generated by peripheral devices such as keyboards printers communication cards etc. They are also generated by coprocessors. It is not possible to deactivate external interruptions. These interruptions are not sent directly to the CPU but rather they are sent to an integrated circuit whose function is to exclusively handle this type of interruptions. The circuit called PIC8259A is controlled by the CPU using for this control a series of communication ways called paths. Software interruptions Software interruptions can be directly activated by the assembler invoking the number of the desired interruption with the INT instruction. The use of interruptions helps us in the creation of programs and by using them our programs are shorter it is easier to understand them and they usually have a better performance mostly due to their smaller size. This type of interruptions can be separated in two categories the operative system DOS interruptions and the BIOS interruptions. The difference between the two is that the operative system interruptions are easier to use but they are also slower since these interruptions make use of the BIOS to achieve their goal on the other hand the BIOS interruptions are much faster but they have the disadvantage that since they are part of the hardware they are very specific and can vary depending even on the brand of the maker of the circuit. The election of the type of interruption to use will depend solely on the characteristics you want to give your program speed using the BIOS ones or portability using the ones from the DOS. Most common interruptions Table of Contents Int 21H DOS interruption Multiple calls to DOS functions. Int 10H BIOS interruption Video input output. Int 16H BIOS interruption Keyboard input output. .