HAL (hardware abstraction layer)
A Windows NT executive component providing platform-specific support for the Windows NT Kernel, I/O Manager, kernel-mode debuggers, and lowest-level device drivers. The HAL exports routines that abstract platform-specific hardware details about caches, I/O buses, interrupts, etc. and provides an interface between the platform’s hardware and the system software. For example, the HAL implements a routine to map each device driver’s bus-relative device interrupt vector to a system-assigned vector with a corresponding platform-specific hardware priority (DIRQL), as well as several routines that provide DMA-transfer support.