H

hardware branch

The hardware archive root key in the registry that is a superset of the memory-resident hardware tree. Although the hardware tree contains information only about those devices currently detected and running in the system, the registry contains a complete list of all hardware ever installed on the particular computer. The hardware root key is \\Hkey_Local_Machine\Hardware.

hardware tree

A record in RAM of the current system configuration based on the configuration information for all devices in the hardware branch of the registry. The hardware tree is created each time the system is started or whenever a dynamic change occurs to the system configuration.

HCI

Host controller interface. System-level interface supporting USB.

HCL

Hardware Compatibility List. See WHQL.

HCT

Hardware Compatibility Tests. A suite of tests from WHQL to verify hardware and device driver operations under a specific operating environment. These tests exercise the combination of a device, a software driver, and an operating system under controlled conditions to verify that all components operate properly.

HDC

Hard disk I/O controller.

HDTV

High-definition TV. A proposed standard that recommends doubling the current 525 lines per picture to 1050 lines, and increasing the screen aspect ratio (that is, width to height) from the current 12:9 to 16:9, which would create a television screen shaped more like a movie screen.

HID

Human Interface Device.

high resolution

An adjective describing improvement in display image quality as a result of increasing the number of pixels per square inch.

HSB

Hue-saturation-brightness. With the HSB model, all colors can be defined by expressing their levels of hue (the pigment), saturation (the amount of pigment), and brightness (the amount of white included), in percentages.

hue

The color tint of an image. The color of the analog video signal is determined by three factors: hue, saturation, and luminance.

Human Interface Device Specification

The device class definition developed by the USB standards group for HIDs. Serves as the basis for the WDM input device support, and unifies input devices by providing flexible data reporting, typeless data, and arrayed and variable input and output.

Hz

Hertz (cycles per second).