A Comprehensive Guide to BIOS and DOS Interrupts. what is BIOS and DOS interrupts?

 

In the ever-evolving world of computing, understanding the intricacies of BIOS (Basic Input/Output System) and DOS (Disk Operating System) interrupts opens doors to unleashing the full potential of system functionality. These interrupts provide programmers with a gateway to tap into low-level system operations, enabling them to interact with hardware and enhance system capabilities. In this engaging blog, we will embark on a journey into the realm of BIOS and DOS interrupts, exploring their profound significance, practical applications, and the exciting opportunities they offer.

 

BIOS Interrupts

The BIOS, an integral part of computer firmware, assumes a pivotal role in initializing hardware components during system startup. BIOS interrupts serve as indispensable conduits between the operating system and the underlying hardware, providing a standardized interface for accessing system services. Delve into the captivating world of BIOS interrupts, where the following aspects come to light:

 

a) Purpose: BIOS interrupts open avenues to access a diverse range of system services. These encompass reading keyboard input, displaying text on the screen, controlling interrupts, and accessing disk drives, among others.

 

b) Interrupt Vector Table: Embodied within the BIOS Interrupt Vector Table (IVT) are interrupt vectors—memory locations storing addresses of specific BIOS functions. By invoking the corresponding interrupt number, programmers can seamlessly engage these functions.

 

c) Software Interrupt Instructions: To initiate a BIOS interrupt, programmers employ software interrupt instructions like the INT instruction in x86 assembly language. Executing the INT instruction triggers a specific interrupt number, prompting the processor to transfer control to the relevant BIOS routine.

 

d) Interrupt Handlers: BIOS interrupts rely on pre-established interrupt handlers to execute desired functions. While programmers can tailor these interrupt handlers or create their own, the flexibility to customize system behavior is an enticing prospect.

 

DOS Interrupts

Within the Disk Operating System (DOS) environment, DOS interrupts, also known as software interrupts, serve as gateways to low-level system functions and services. Harnessing the power of DOS interrupts empowers programmers to interact with hardware devices, execute file operations, and effectively manage system resources. Dive into the captivating world of DOS interrupts, where the following aspects unravel:

 

a) Purpose: DOS interrupts facilitate a myriad of system operations, encompassing file input/output, keyboard input, screen output, disk operations, memory allocation, and process management, among others.

 

b) Interrupt Vector Table: Aligned with BIOS interrupts, DOS interrupts employ an Interrupt Vector Table (IVT) housing addresses of interrupt handlers. Each interrupt number corresponds to a specific DOS function, providing a structured approach to accessing system services.

 

c) Software Interrupt Instructions: To invoke DOS interrupts, programmers utilize software interrupt instructions like the INT instruction. By specifying the desired interrupt number, programmers gain seamless access to the corresponding DOS function.

 

d) Function Parameters: DOS interrupts often necessitate passing parameters to specify desired operations. These parameters may encompass file handles, memory addresses, flags, and other relevant data, enabling programmers to tailor their actions accordingly.

 

e) Error Handling: DOS interrupts equip programmers with error codes or flags, indicating the success or failure of a particular operation. By examining these error codes, programmers can gracefully handle exceptions or errors that may arise during system operations.

 

Benefits and Applications

The inherent benefits and practical applications of BIOS and DOS interrupts are boundless, extending their influence to diverse domains, including:

 

a) Hardware Interaction: BIOS and DOS interrupts empower programmers to directly interact with hardware devices, facilitating tasks such as reading from or writing to disk drives, communication with input/output ports, and control over interrupt requests.

 

b) System Configuration: BIOS interrupts unlock the ability to retrieve and modify essential system configuration settings, such as date, time, keyboard layouts, and hardware information. This flexibility empowers programmers to tailor system settings to suit their specific needs.

 

c) System Programming: DOS interrupts offer programmers an avenue for low-level system programming, providing access to system resources and services. This opens doors to tasks such as file manipulation, memory management, and process control, enabling the creation of efficient and customized system operations.

 

d) Device Drivers: The role of interrupts in device driver development is invaluable. By harnessing interrupts, programmers can create robust and efficient device drivers that seamlessly interface with hardware devices, enabling optimized data transfer and device control.

 

Conclusion:

The realm of BIOS and DOS interrupts presents a captivating avenue for programmers to amplify system functionality and engage with hardware at a low-level. These interrupts grant access to an array of system services and resources, fostering customization and empowering programmers to harness the full potential of their systems. By embracing the intricacies of BIOS and DOS interrupts, programmers embark on a journey of endless possibilities, propelling system capabilities to new horizons. So, take a leap into this fascinating world, and unlock the true potential of your computing experience.