Epson 3865X Plus User Manual page 323

Operating system
A collection of programs (such as MS-DOS or MS OS/2) that
manages a computer's operations. The operating system
determines how programs run on the computer and supervises
all input and output.
Option card
A circuit board you install inside the computer to provide
additional capabilities, such as a modem.
Parallel
The type of interface that transmits all the bits in a byte of data
simultaneously over separate lines. See Interface and Serial.
Parameter
A qualifier added to a command that tells MS-DOS what
particular conditions to look for and specifies information such
as what data you want to process and where to locate or store a
file.
Parity
A method used to verify the accuracy of data transmissions by
adding a bit that makes the total of the byte odd for odd parity
or even for even parity.
Partition
(1) The area defined on a hard disk for use by an operating
system; (2) to divide a hard disk into separate sections or logical
drives. You can define a primary partition and an extended
partition on the hard disk.