1) In computers, a hardware abstraction layer (HAL) is a layer of programming that allows a computer operating system to interact with a hardware device at a general or abstract level rather than at a detailed hardware level. Windows 2000 is one of several operating systems that include a hardware abstraction layer. The hardware abstraction layer can be called from either the operating system's kernel or from a device driver. In either case, the calling program can interact with the device in a more general way than it would otherwise.
2) "HAL" was the name of the computer that ran the spaceship in Stanley Kubrick and Arthur C. Clarke's film 2001.