A device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device.

A driver typically communicates with the device through the computer bus or communications subsystem to which the hardware is connected. When a calling program invokes a routine in the driver, the driver issues commands to the device. Once the device sends data back to the driver, the driver may invoke routines in the original calling program. Drivers are hardware-dependent and operating-system-specific. They usually provide the interrupt handling required for any necessary asynchronous time-dependent hardware interface.

Because of the diversity of modern hardware and operating systems, many ways exist in which drivers can be used. Drivers are used for interfacing with:

* Printers
* Video adapters
* Network cards
* Sound cards
* Local buses of various sorts - in particular, for bus mastering on modern systems
* Low-bandwidth I/O buses of various sorts (for pointing devices such as mice, keyboards, USB, etc.)
* computer storage devices such as hard disk, CD-ROM and floppy disk buses (ATA, SATA, SCSI)
* Implementing support for different file systems
* Implementing support for image scanners and digital cameras

Common levels of abstraction for device drivers are

* For hardware:
o Interfacing directly
o Writing to or reading from a Device Control Register
o Using some higher-level interface (e.g. Video BIOS)
o Using another lower-level device driver (e.g. file system drivers using disk drivers)
o Simulating work with hardware, while doing something entirely different
* For software:
o Allowing the operating system direct access to hardware resources
o Implementing only primitives
o Implementing an interface for non-driver software (e.g. TWAIN)
o Implementing a language, sometimes quite high-level (e.g. PostScript)

Choosing and installing the correct device drivers for given hardware is often a key component of computer system configuration.

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This entry was posted on Monday, March 23rd, 2009 at 1:23 pm and is filed under technology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.