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G
Glossary
code39
nugget
helconital
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.
handshake event
A communications 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.
HIBC
Health Industry Bar Code standard. A modified version of Code 39 that has 43
characters, uses 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.
home
The viewport's home position is the upper left corner of the reader's virtual
display.
horizontal reading angle
The horizontal angle of a reader's laser scanner to a bar code label. The
optimum horizontal reading angle is near zero degrees.
host computer
A PC or other computer connected to the JANUS reader. Also called the host.
human-readable
A character 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.
image file
An image file contains all the files you want to load onto the reader's ROM
drives. Because ROM drives are implemented in flash memory, you can use
DOS commands to read from drive C or D, but you must use special utilities to
write to drive to them.
G-13
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