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Glossary
Fuse
is an electrical safety device consisting of a metal wire (within a glass
tube) that melts and interrupts the circuit when the amperage exceeds a
predetermined point.
Hardware
is the set of tangible parts of a computer system: the computer,
printer, and other peripherals - everything in a computer system except the
information contained in that system.
Input/Output (I/O)
is the exchange of data between the computer and the
printer. For example, your Gemini takes input from the computer in the form
of data; when it cannot accept any more for the time being, Gemini sends
output in the form of a "BUSY" signal, telling the computer to wait.
Interface
is the common boundary (physical connection) between two
hardware items (such as your computer and Gemini) or between two systems.
The interface permits the transfer of data and intelligent communication.
Hexadecimal
is the mathematical numeration system with a base of 16
(compared with 2 in the binary system and 10 in the decimal system).
Appendix I presents the hexadecimal and decimal equivalents for the ASCII
coded characters.
K stands for kilobyte, specifically 1,024 bytes. Computer memory is often
expressed in terms of K.
LED,
see Diode.
Line Feed (LF)
is a paper-advancing function that is initiated by pressing the
LF button on the control panel of your Gemini. When this button is depressed,
the paper advances one line; when this switch is held down, consecutive
paper-feeds result for as long as the button is depressed.
Local
defines a condition in which the communication link between the
printer and the computer has been interrupted and the printer is not on-line.
The
on-line control panel button
is used to switch the printer between being
local and on-line with the computer.
Macro Instruction
is the ability of a peripheral device (Gemini-10Xl15X) to
accept a single control code to do the work of a multi-command series of
codes.
Main memory
refers to the electronic circuits that are instantaneously
available to the computer, circuits containing storage of the software and
data currently being used.
Microprocessors
are the "brains" of the personal computer. The most
commonly used types, each about the size of a stack of three dimes, are the
8080, Z-80, and the 6502.
Megabyte
is equivalent to 1,024 kilobytes of memory. Note: Because
computers work with binary numbers, K equals 2
10
(or 1,024) bytes, rather than
a thousand bytes as "K" would imply; similarly, a megabyte equals 2
10
K.
256
I
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