'''Hal.dll''' is the core file of the [[Windows NT]] family of [[operating systems]] that provides and handles the interaction of software and hardware via the' [[Hardware Abstraction Layer]]., Withoutwhich hal.dllallows beingapplications present,to anyaccess machinedevices runningin athe [[Windowssystem NT]]without basedknowledge [[operatingof system]]the willspecific failprotocol toused function,by if itany evenone bootsdevice.
Although drivers for most hardware are contained in external files, core drivers (which are required to support the kernel) are compiled into Hal.dll. Different sets of drivers may be selected depending on whether the system uses multiple processors, the presence of [[ACPI]] or an [[APIC]], etc. On earlier versions of Windows NT, the CPU's architecture was also considered.
Windows includes several HALs to support different kinds of hardware; the appropriate HAL is chosen during the initial installation of Windows. Generally speaking, the determining factors for HAL selection are uni- vs. multi-processor [[CPU]], [[Advanced Configuration and Power Interface|ACPI]] vs. non-ACPI, and [[APIC]] vs. [[Programmable Interrupt Controller|PIC]].
