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H___________________________
Handshake
The communication that occurs between devices in order to determine the method and speed of data transfer to be used.
Hard Disk
A disk made of metal and permanently sealed into a drive cartridge. A hard disk can store every large amounts of information.
Hardware
Computer machinery, such as the CPU, disk drives, monitor, and printer. Contrast with software.
Hardware Handshaking
Hardware (usually a modem cable) which handles handshaking (data flow control) automatically. Most new modem cables have hardware handshaking.
HBA
Host Bus Adapter. An integrated circuit that supplies a bus connector to a computer system. Also referred to as Host Adapter.
HD (high-density) connector
A connector in which the pins are closely packed in order to save space. High-density A-cable connectors have just as many pins as low-density A-cable connectors but are smaller than the low-density ones.
Header Field
Four bytes recorded at the beginning of each sector which tell the address of the sector (expressed as a Logical Block Number) and the mode in which the sector is recorded.
Helical Scan (8mm Helical Scan)
The 8mm helical scan tape backup system provides 2 to 5 GB of storage. Using an 8mm video cassette tape as a recording medium, data is recorded using the same rotating head technique as a DAT cartridge.
HFS
The file system used by the Macintosh operating system to organize data on hard and floppy disks. Can also be used for CD-ROMs.
High Memory Area (HMA)
The first 64K of extended memory in an IBM PC or compatible computer. This area is used by Windows and by some applications. MS-DOS can also be "loaded_high"- loaded into the HMA to make more room in conventional memory.
High Sierra Format
The standard logical format for CD-ROM originally proposed by the High Sierra Group, on which the ISO 9660 standard is based; essentially identical to ISO 9660. High Sierra is no longer used.
HMA
See High Memory Area.
Host
The computer system in which a SCSI host adapter is installed. It uses the SCSI host adapter to transfer information to and from devices attached to the SCSI bus.
Host Adapter
The controller card used to communicate with and control devices. A SCSI host adapter is used to attach and communicate with SCSI devices.
Hot Key
A keystroke or combination of keystrokes intended for activating a RAM-resident program on IBM PC and compatible computers.
HTTP
The Hypertext Transfer Protocol, the basis of the World-Wide Web.
Hybrid
Under the Orange Book standard for recordable CD, hybrid means a recordable disc on which one or more sessions are already recorded, but the disc is not closed, leaving space open for future recording. However, in popular use, the term "hybrid" often refers to a disc containing both DOS/Windows and Macintosh software, which on a DOS/Windows platform is seen as a normal ISO 9660 disc, while on a Mac it appears as an HFS disc.
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