What Is a Device Driver? Definition, Types, and Applications
A device driver is a program without a UI that manages hardware attached to a computer and supports its functioning.
A device driver is defined as a software program without a user interface (UI) that manages hardware components or peripherals attached to a computer and enables them to function with the computer smoothly. This article explains the working of device drivers, their various types, and five critical applications.
Table of Contents
What Is a Device Driver?
A device driver is a software program without a user interface (UI) that manages hardware components or peripherals attached to a computer and enables them to function with the computer smoothly.
A device driver is a specialized software that operates a particular computer-connected device—offering a software interface to the hardware allows operating systems and other computer applications to access hardware functionalities.
The hardware is linked to a computer bus/communication subsystem via which device drivers interact with the device. They are hardware-dependent and operating-system-specific (OS). They offer the interrupt processing essential for any time-dependent asynchronous hardware interface.
A device driver’s primary objective is to allow computers and network hardware components to interface and interact with specific devices. They handle requests made by the kernel concerning a particular type of device. Device drivers define messages and mechanisms through which the computer’s operating system and applications can access the device or make requests for the device. They also handle device responses and messages for delivery to the computer.
How device drivers function
Device drivers operate inside the OS kernel layer. They work in a highly privileged environment because they need low-level access to hardware operations to function. They enable the computer’s operating system (OS) to interface with the hardware for which they were developed. And through a computer bus that links the device to the computer, the drivers and the device communicate.
Device drivers must receive advice from the operating system to access and execute device instructions. After completing the job, they transmit the hardware device’s output or message to the operating system. Devices such as modems, routers, speakers, keyboards, and printers require device drivers to operate.
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Understanding device driver development
Device drivers enable peripheral devices, such as printers or keyboards, to interact with the computer. The following outlines the steps developers or programmers can take while developing device drivers for operating systems such as Windows, Linux, or macOS.
1. Know the equipment
When designing a device driver, programmers must have an in-depth grasp of the platform’s hardware. They should know the bus interface that the hardware uses to communicate with the host and the location of the device driver software. They should read the device datasheet to understand the relevant terms and definitions. They should also know the method through which data transfer takes place.
If the primary device is a system on chip, developers should know how the driver interacts with its firmware and command protocols. Additionally, developers should be prepared for documentation to fall short when handling a new type of hardware. Thus, they should be ready to perform more tests than usual.
2. Write the driver code
In this step, developers should obtain a working prototype of their preferred hardware. Then they should start writing the kernel mode driver.
If a device is incorrectly designed, drivers running in user mode may cause a system crash. Similarly, if anything goes wrong when drivers are operating in highly privileged settings, operational concerns may occur. Thus, developers should take advantage of the information in the driver development documentation available for the selected operating system, be it Windows or Linux.
The first device driver functions that are developed are the load and unload functions. When the operating system starts and stops, these functions are called. One of the primary responsibilities of the load/unload functions is to detect whether the hardware is plugged into the system or not. Users can detect hardware by using the device ID specified by the specific bus. If the hardware is plugged in, then the load function is successful. If not, call the unload function.
3. Initialize the hardware
Once the device can detect the hardware, the next step is initializing it. The type of initialization required may differ depending on the kind of hardware. Initialization can range from writing to the device register to downloading a microcode onto the device and communicating on a long-term basis using proprietary command protocols.
4. Control the hardware
Controlling the hardware is only possible if developers can initialize and communicate with the hardware. The control process depends on the device. Developers should consider whether the device will simply relay data from one device to another.
For instance, when relaying music from a smartphone to a speaker. They should also consider whether the device will continuously send data and instructions to other devices. For instance, telling a printer to print black and white on one side of paper followed by a double-sided print in color.
The device driver turns on data settings like playing speed and fast-forwarding input through the computer into commands for the device. Unlike the previous three steps, this one may take more time. The first three steps might be a one-time operation as the OS loads. However, developers might need to perform Step 4 several times after the OS is set up and running. Users might sometimes merge the 3rd and 4th steps into a single step.
5. Begin data communication with the hardware
Several devices deal with some form of data, be it audio or video. Once the device is initialized, developers can send a steady stream of data as required. The device driver acts as a pipe between the higher-level application and the lower-level hardware or firmware for data transfer.
As noted in the first step, developers should know the protocols designed for data communication. Data transfers might be interrupt-driven or polled. The OS provides facilities such as messaging or interrupt service routines used during the data transfer process. Developers should start by transferring a single packet of data and ensuring that the whole process from steps 1 to 3 works fine.
6. Control data communication
In this step, developers need to control the data transfer and manage communication in several situations. When problems arise, users should prevent the peripheral devices from sending the same error message. In an audio stream, when there is a buffer overflow or a significant problem with the sound quality, they should send a stop command.
7. Test the driver and debug it
Testing is a crucial aspect. Developers should test the device to ensure it is recognized and initialized. They should also run functional tests to ensure the device drivers work as expected. They should also be ready to make changes to the hardware to ensure smooth operation. Additionally, developers should test the device drivers on different operating system versions to verify that they are forward and backward-compatible. Once the device driver works, developers can register it.
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9 Types of Device Drivers
Developers may distinguish the following types of device drivers:
1. Kernel device drivers
Kernel device drivers consist of some generic hardware loaded with the operating system (OS) as part of the OS. They include motherboards, processors, and BIOS. They are invoked and loaded into the random-access memory (RAM) when required. When several of them are operating at the same time, the machine can slow down. Thus, there is a minimum requirement for each OS.
Kernel device drivers are layered. Higher-level drivers, such as file system drivers, receive data from applications, filter it, and pass it to a lower-level driver, supporting drive functionality. Kernel device drivers are implemented as discrete and modular components that have a well-defined set of required functionalities.
2. User-mode device drivers
User mode device drivers execute in user mode. They refer to device drivers that users may trigger during a session. When using a system, users may have their own external devices that they bring to use, such as external plug-and-play devices. These devices also require drivers to function. In Windows systems, user-mode device drivers provide an interface between a Win32 application and kernel-mode drivers or other operating systems. Users can write these drivers to the disk to reduce strain on computer resources.
3. Character drivers
Character device drivers provide unstructured access to the hardware. They transfer data to and from devices without using a specific device address. They allow the reading or writing of one byte at a time as a stream of sequential data. Character drivers do not handle input/output (I/O) through the buffer cache, so they are more flexible in handling I/O. They are paired with block devices to circumvent the buffer cache to offer raw I/O operations straight to the program address space of the user.
Additionally, they provide additional interfaces such as I/O control commands, device polling, and memory mapping. Examples are modems and bus controllers.
4. Block drivers
Block device drivers provide structured access to the hardware. They use file system block-sized buffers from a buffer cache supplied by the kernel to perform I/O. A buffer cache is a memory pool established by the kernel to store frequently accessed blocks via block devices. The buffer cache reduces the amount of I/O queries that need an I/O operation from the device.
In addition, block device drivers provide accessible block-oriented I/O and demonstrate data durability. They take a file system request and issue the I/O procedures to the disk to transfer the requested block. Examples are USB memory keys and disk drives.
5. Original equipment manufacturer (OEM) drivers
Device drivers can be categorized as generic or OEM-related. Generic drivers refer to device drivers with their operating software bundled into the OEM hardware. One can use generic drivers with different brands of a particular device type. For instance, Linux works with several generic drivers that function without the need to install any other software manually.
OEMs can create their proprietary device drivers, which need to be installed separately after installing the OS. OEM drivers enable hardware such as keyboards to communicate with the host OS. For instance, OEM drivers enable functions such as integrating the lighting control system with OEM hardware in Google Assistant and Alexa.
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6. Virtual device drivers
Virtual device drivers are essential in controlling virtual machines or VMs. They operate in both virtualization and non-virtualization environments. In virtualization environments, these drivers are used to emulate the hardware of the host device. They control or manage the resource hardware of the host device to ensure that both the guest and host device run as expected.
For example, when a guest operating system works on a host, it makes function calls to virtual device drivers to access the hardware. In addition, they imitate processor-level occurrences like interrupts and transmit them to the virtual machine.
7. BIOS
The basic input output system (BIOS) is the most fundamental driver on a computer. It is located in a read-only memory (ROM) chip, which ensures that BIOS will be available even when the hard disk is formatted. It is in charge of booting a computer and providing it with a set of instructions during this process. It also performs power-on self-tests (POST) that are required during startup. The BIOS also provides drivers for the basic hardware, such as keyboards and monitors, to ensure that they interface with the operating system to function as intended.
8. Motherboard drivers
Motherboard drivers are simple applications that both Windows and Linux may utilize. They exist within the operating system and enable fundamental computer operations. These drivers comprise applications that allow the keyboard and mouse’s USB devices and I/O ports to work. Some motherboards have drivers that support video and audio.
Motherboard drivers are specific for the chipset model, such as B460 for Intel computers. To realize the motherboard’s full potential and enable components connected to it to work correctly, users may need to install additional drivers.
9. Open-source drivers
Open-source drivers refer to drivers that are released under a free and open-source license. For instance, open-source graphic drivers control the output to the display if the display is part of the graphics hardware. The source code for open-source drivers is available to everyone, making software collaborations easier. They are more trustworthy as people can check them for any malicious code.
Open-source drivers offer more privacy. If they track users, people can redistribute a copy of the software with the tracking removed. Open-source drivers last longer as more people continue to make improvements, thus ensuring that even when the company stops distributing them, a copy remains.
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Applications of Device Drivers
These essential building blocks of personal and enterprise computing are used in the following ways:
1. Device drivers for accessing storage systems
Computer storage systems allow users to store data and make it available on demand. They include external and internal devices such as USB flash drives, hard drives, and network-attached storage. Drivers in storage systems enable them to interact with the computer. This ensures that the computer can access its internal or external storage systems, query their information, and allow data transfer.
Connecting storage devices to the computer without drivers becomes difficult as the OS does not detect them. Usually, hard disks and CD-ROMs are recognized by the OS and do not require drivers to be manually installed. Users must install drivers from the manufacturer’s website if they are not automatically detected.
2. Device drivers for input and output devices
The computer’s OS interacts with device drivers to ensure its hardware functions as expected. Input devices include mice and keyboards, while output devices include display devices such as monitors. Keyboards, mice, and monitors are categorized as plug-and-play devices.
Usually, the drivers for plug-and-play devices are generic and do not require manual installation, as the computer’s OS recognizes them and installs them automatically. However, if an external device is not a plug-and-play device, users may need to manually install the drivers from the installation disc or download them. This will enable the OS to recognize these devices.
3. Device drivers for digital cameras
A digital camera driver is a program that allows communication between it and other devices, such as computers. Without the drivers, the OS will not detect this device. Most digital cameras are only compatible with the Windows OS, as Linux systems lag.
Digital camera drivers allow for the transfer of photos from the camera to the computer. They enable digital cameras to print photos using the PictBridge standard directly to a PictBridge-capable computer printer without needing a computer. Drivers in the video output port allow users to display pictures on television by selecting one video or photo at a time.
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4. Drivers for mobile operating systems like Android
Mobile phones have drivers to enable them to communicate with computers. Drivers come bundled with the firmware on most phones, which allows computers to load them up to support hardware as the OS is not specified. However, sometimes users may need to install OEM PC software first for drivers to be installed and allow data transfer.
Drivers allow for the integration of peripheral devices such as game controllers or keyboards based on operating systems such as Android Things and Android. The drivers enable access and control of the hardware. Additionally, they allow smart devices to work with custom applications.
5. Device drivers for superior video performance
Graphic cards are core components of a computer system and are responsible for superior video performance in computers, games, or other graphic-intensive tasks. Graphic drivers allow graphic cards to interact with the computer’s operating system and are thus essential to getting top performance from the graphic cards.
Updating graphic drivers and other Windows 11 (or older) drivers can give users a speed boost, fix problems, and sometimes even provide users with new features. For instance, updating game drivers can increase frames per second, reducing lag.
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Takeaway
As consumers and businesses increasingly use devices and peripherals, device drivers are essential to IT infrastructure. Modern driver technology can improve computer functioning by reducing resource consumption and boosting speed. That is why it is necessary to know how drivers operate and have a regular driver patching and update schedule so that the entire device ecosystem works smoothly.
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