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Interface
LPI
Parallel Interface
Parity
PROM
The connection between
two
pieces
of
equipment,
such
as
between a computer and a printer. The
two
basic types
of
interface are parallel and serial.
The
word
is
loosely used to mean either the
method
of
connection
or
the actual hardware used
to connect equipment,
including
the circuits that
-
control communication.
As
a verb, it usually
means the act
of
making the connection.
Lines
Per
Inch: a measure
of
line spacing.
When
the
line
spacing
is
6
LPI,
the distance between the
bottom
of
one
line
of
print
and the bottom
of
the
next
is
1/6 inch.
An interface in
which
the eight bits comprised by
a byte
of
data are transmitted simultaneously over
eight separate wires.
A method
of
checking for data transmission errors
used in some serial interfaces. The computer adds
a
bit
(the
"parity
bit")
to each byte
of
data
so
the
total
number
of
1 s
is
either always even ("even
parity") or always odd
("odd
parity"). The printer
checks each
incoming
byte plus parity
bit
to make
sure the parity
is
correct. If the parity
is
not cor-
rect, the data
has
not been sent (or received) prop-
erly. The printer
will
signal when
it
detects a
"parity
error."
Programmable Read-Only
Memory:
ROM
that can
be programmed,
but
only
with
special equipment,
so
for most people PROM and
ROM
are the
same. Some MICROLINE options consist
of
a
set
of
PROMs to replace those in the standard printer.
The
new
PROMs tell the printer
to
interpret con-
trol codes differently.
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