Hardware abstraction layer

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A hardware abstraction layer ( english Hardware Abstraction Layer , HAL ) is a layer of an operating system that the kernel and all the rest of the software from the hardware isolated.

Hardware can only be accessed by the hardware abstraction layer; all other software can only access it through the intermediary of the hardware abstraction layer. This abstraction makes it easier to adapt the operating system to different processor architectures because only part of the hardware abstraction layer has to be changed. It also makes it easier to program device drivers because these are based on the hardware abstraction layer.

In Windows operating systems, the HAL is located at C: \ Windows \ system32 \ hal.dll .

The NetBSD operating system , which is available for over 50 different platforms , most clearly shows the potential of the concept.

The firmware of a computer can take over tasks of the hardware abstraction. On x86 computers, the firmware is usually called BIOS . However, more modern operating systems use their own hardware drivers after booting , so they have their own hardware abstraction layer.

See also

literature

  • Abraham Silberschatz, Peter Bear Galvin, Greg Gagne: Operating System Concepts. Sixth Edition. 2002, ISBN 0-471-41743-2

Individual evidence

  1. ↑ Advanced RISC Computing Specification (PDF; 383 kB) MIPS Technologies . P. 23. Retrieved February 26, 2013.
  2. ^ Windows NT Hardware Abstraction Layer (HAL) . Microsoft. Retrieved May 7, 2009.
  3. ↑ Portability and supported hardware platforms . The NetBSD Foundation. Retrieved May 12, 2009.