Quick Reference Guide

Glossary 411
GMT
Abbreviation for Greenwich Mean Time, which is the standard time common to
every place in the world. GMT nominally reflects the mean solar time along the
prime meridian (0 longitude) that runs through the Greenwich Observatory
outside of London, UK.
graphics coprocessor
See coprocessor.
graphics mode
A video mode that can be defined as x horizontal by y vertical pixels by z colors.
GUI
Acronym for graphical user interface.
GUID
Globally unique identifier. A 16-byte identifier based on the host's network
interface card (NIC) address and time stamp.
h
Abbreviation for hexadecimal. A base-16 numbering system, often used in
programming to identify addresses in the system's RAM and I/O memory
addresses for devices. The sequence of decimal numbers from 0 through 16, for
example, is expressed in hexadecimal notation as: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B,
C, D, E, F, 10. In text, hexadecimal numbers are often followed by h.
HBA
Abbreviation for host bus adapter. A PCI adapter card that resides in the system
whose only function is to convert data commands from PCI-bus format to storage
interconnect format (examples: SCSI, Fibre Channel) and communicate directly
with hard drives, tape drives, CD drives, or other storage devices.
heat sink
A metal plate with metal pegs or ribs that help dissipate heat. Most
microprocessors include a heat sink.
HMA
Abbreviation for high memory area. The first 64 KB of extended memory above
1 MB. A memory manager that conforms to the XMS can make the HMA a direct
extension of conventional memory.
Also see XMM.