IBM Models 5, Service Manual

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display, and printing of DBCS characters requires
hardware and programs that support DBCS. Contrast
with
single-byte character set .
DRAM. Dynamic RAM. See RAM .
driver. A software component that controls a device.
dump. (1) To record, at a particular instant, the
contents of all or part of one storage device in another
storage device. Dumping is usually for the purpose of
debugging. (T) (2) Data that has been dumped. (T)
DVD-ROM. Digital-video-disk read-only memory.
E
error message. A message that is issued because an
error has been detected.
F
FCC. See Federal Communications Commission.
feature. A part of an IBM product that may be
ordered separately by the customer.
Federal Communications Commission (FCC). A
board of commissioners appointed by the President
under the Communications Act of 1934, having the
power to regulate all interstate and foreign
communications by wire and radio originating in the
United States.
field. On a data medium or a storage medium, a
specified area used for a particular category of data; for
example, a group of character positions used to enter
or display wage rates on a panel. (T)
file. A named set of records stored or processed as a
unit. (T) For example, an invoice may form a record
and the complete set of such records may form a file.
See also
data set .
flash memory. A data-storage device that is
programmable, erasable, and does not require
continuous power. The chief benefit of flash memory
over other programmable and erasable data storage
devices is that it can be reprogrammed without being
removed from the circuit board.
formatted diskette. A diskette on which track and
sector control information has been written and that
can be used by the computer to store data.
Note:
A
diskette must be formatted before it can receive data.
frame . (1) The unit of transmission in some LANs,
including the IBM Token-Ring Network and the IBM
PC Network. It includes delimiters, control characters,
information, and checking characters. On a token-ring
network, a frame is created from a token when the
token has data appended to it. On a token-bus network
(IBM PC Network), all frames including the token
frame contain a preamble, start delimiter, control
address, optional data and checking characters, end
delimiter, and are followed by a minimum silence
period. (2) A housing for system elements. (3) In
synchronous data link control (SDLC), the vehicle for
every command, every response, and all information
that is transmitted using SDLC procedures. Each frame
begins and ends with a flag.
function. (1) A specific purpose of an entity, or its
characteristic action. (A) (2) In data communications, a
system action such as a carriage return or line feed. (A)
H
hard-disk drive. In a personal computer system unit,
a disk storage device that reads and writes on rigid
magnetic disks. It is faster and has a larger storage
capacity than a diskette and is permanently installed.
Synonymous with
fixed disk .
HID. See human interface devices .
hot pluggable. Refers to a hardware component that
can be installed or removed without disturbing the
operation of any other resource that is not connected
to, or dependent on, this component.
human interface devices (HID). Devices which allow
humans to interact and communicate with a computer.
Examples are a keyboard or a mouse.
hot plugging. Process of installing connections to the
serial bus while the system is running and without
powering down.
hot unplugging. Process of removing connections
from the serial bus while the system is running and
without powering down.
hypertext. (1) A method of presenting text in discrete
units, or nodes, that are connected by links for
navigation. (2) Text designed to be read or accessed in
a nonlinear manner using nodes that are connected by
links for navigation.
I
I/O. See input/output .
I/O device. A device in a data processing system by
means of which data can be entered into the system,
received from the system, or both. (I) (A)
IBM Disk Operating System (DOS) .
A disk
operating system based on MS-DOS that operates with
all IBM-compatible personal computers.
IEEE. Institute of Electrical and Electronics Engineers.
Glossary
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