This is because they have better information than most outsiders about the design of their hardware. The task of writing drivers thus usually falls to software engineers or computer engineers who work for hardware-development companies. These factors make it more difficult and dangerous to diagnose problems. Even drivers executing in user mode can crash a system if the device is erroneously programmed. In contrast, most user-level software on modern operating systems can be stopped without greatly affecting the rest of the system. Because drivers require low-level access to hardware functions in order to operate, drivers typically operate in a highly privileged environment and can cause system operational issues if something goes wrong.
Writing a device driver requires an in-depth understanding of how the hardware and the software works for a given platform function. The commands needed to control a 16550 UART are much different from the commands needed to control an FTDI serial port converter, but each hardware-specific device driver abstracts these details into the same (or similar) software interface. At a lower level, a device driver implementing these functions would communicate to the particular serial port controller installed on a user's computer. Programmers can write higher-level application code independently of whatever specific hardware the end-user is using.įor example, a high-level application for interacting with a serial port may simply have two functions for "send data" and "receive data". The main purpose of device drivers is to provide abstraction by acting as a translator between a hardware device and the applications or operating systems that use it. They usually provide the interrupt handling required for any necessary asynchronous time-dependent hardware interface. Once the device sends data back to the driver, the driver may invoke routines in the original calling program.ĭrivers are hardware dependent and operating-system-specific. When a calling program invokes a routine in the driver, the driver issues commands to the device (drives it).
A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details about the hardware being used.Ī driver communicates with the device through the computer bus or communications subsystem to which the hardware connects. In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. For other software drivers, see Driver (software). This article is about device drivers for hardware.
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