From G to H

A LAN product that allows devices on two different subnets to communicate with each other.

A bitmap picture downloaded to the printer by the host before printing.

Graphics mode
One of two display modes on the reader. When the reader is set to use Graphics mode, you see a 128 x 160 pixel display size. You can use the reader's CGA display as a viewport to move around and see a 200 x 640 pixel virtual display. Contrast with Text mode.

group address
A type of address that is used by the host to locate two or more devices.

guard bars
The bars that are at both ends and at the center of a UPC and EAN symbol. They provide reference points for scanning, similar to start/stop characters.

Graphical user interface.

half duplex
A data communication term pertaining to an alternate, one direction at a time, transmission. See also full duplex.

hand-held scanner
A scanner held and operated by a human. The scanner is moved to the object to be scanned, instead of moving the object close to the scanner.

handshake event
A communication event that signifies the completion of a data block transmission. The exchange signifies either an affirmative acknowledge (AFF) or a negative acknowledge (NEG). The handshake event is enabled by defining the AFF character to be other than NULL. Some computers use the characters XON and XOFF as handshaking characters.

Physical equipment, such as mechanical, magnetic, electrical, or electronic devices. Contrast with software or method of use.

height sensor
Part of the 7350 Wide Area Bar Code Scanner. Two height sensors, a transmitter, and a receiver send signals across the conveyor belt. When these signals are broken by a package, the package's height can be determined.

helium-neon (HeNe) laser
A type of laser commonly used in bar code scanners. It emits coherent red light at a wavelength of 633 nanometers.

Health industry bar code standard. A modified version of Code 39 that has 43 characters, utilizes the Modulus 43 check character, and reserves some character combinations for special usage.

high memory area (HMA)
HMA is a 64K block of memory, starting 16 bytes below the 1024K mark, and is the first 64K of extended memory. Since HMA can only hold one item, the first program that requests HMA uses it, regardless of the size of the program.

The viewport's home position is the upper left corner of the TE or application screen.

See repeat hop.

horizontal bar code
A bar code or symbol displayed so that its length is parallel to the horizon. The bars are perpendicular to the horizon.

host application
An application running remotely on a host.

host busy
The condition in which the host is processing a request and has not responded, or has not updated the screen. On a 3270 terminal, the OIA shows X-SYSTEM, X-CLOCK, or X-[]. On a 5250 terminal, the OIA shows II (Input Inhibited).

1. A PC or other computer connected to device. 2. If several computers are connected together on a network, the controlling computer is the host. A host can be a desktop, laptop, or notebook PC.

HOSTS file
A database that contains a list of remote hosts' IP addresses and their logical names (aliases) that any device on the network can reach.

hot standby file
If DCM sends a transaction to an application and it does not respond to DCM within a specified period, the application is consider inactive by DCM and any transactions for that application are sent to a temporary file called a hot standby file.

Hot Standby mode
The mode an application is considered to be in by the Model 200 Controller when the controller sends a transaction to an application, and it does not respond within the time set in the Hot Standby timeout. Whenever a device tries to send this application a transaction, the controller can send the device a Hot Standby message. Until the application becomes active again, any transactions destined for that application are written to a Hot Standby file. When the application becomes active, the controller sends it all the transactions in its Hot Standby file.

A character, number, or symbol printed in a font that can be read by a human; as opposed to bar code symbology that can only be read by a machine. See text.