Specifications

Glossary
63
SEC (single edge contact) An Intel processor
packaging design in which the processor and
optional L2 cache chips are mounted on a small
circuit board (much like an oversized memory
SIMM), which might be sealed in a metal and plas-
tic cartridge. The cartridge is then plugged into the
motherboard through an edge connector called Slot
1 or Slot 2, which looks similar to an adapter card
slot. Several variations to the SEC cartridge form
factor exist: The single edge contact cartridge
(SECC) has a cover and a thermal plate; the single
edge contact cartridge 2 (SECC2) has a cover, but
no thermal plate; and the single edge processor
package (SEPP, which is used only with Celeron
processors) has no cover or thermal plate. In imple-
mentations with no thermal plate, the heatsink is
attached directly to the processor package or die.
SECAM Sequential Couleur A Mémoire (sequen-
tial color with memory), the French color TV sys-
tem also adopted in Russia. The basis of operation
is the sequential recording of primary colors in
alternate lines. The image format is 4:3, 625 lines,
50Hz, and 6MHz video bandwidth with a total
8MHz of video channel width.
SECC (single edge contact cartridge)
See SEC.
SECC2 (single edge contact cartridge 2)
See SEC.
sector A section of one track defined with identi-
fication markings and an identification number.
Most sectors hold 512 bytes of data.
security software Utility software that uses a
system of passwords and other devices to restrict an
individual’s access to subdirectories and files.
seek time The amount of time required for a
disk drive to move the heads across one-third of
the total number of cylinders. Represents the aver-
age time it takes to move the heads from one cylin-
der to another randomly selected cylinder. Seek
time is a part of the average access time for a drive.
self-extracting file An archive file that con-
tains its own extraction program. Open it in a file
manager, such as Windows Explorer, to uncompress
the files it contains. Because all types of files,
including Trojans, can be distributed as
.exe files
(the extension also used by self-extracting files),
consider using a program such as WinZip to exam-
ine the contents of an
.exe file before you open it.
semiconductor A substance, such as germa-
nium or silicon, whose conductivity is poor at low
temperatures but is improved by minute additions
of certain substances or by the application of heat,
light, or voltage. Depending on the temperature
and pressure, a semiconductor can control a flow of
electricity. Semiconductors are the basis of modern
electronic-circuit technology.
SEPP (single edge processor package)
See SEC.
sequencer A software program that controls
MIDI file messages and keeps track of music timing.
Because MIDI files store note instructions instead of
actual sounds, a sequencer is needed to play,
record, and edit MIDI sounds. Sequencer programs
enable recording and playback of MIDI files by stor-
ing the instrument, note pitch (frequency), dura-
tion (in real-time) that each note is held, and
loudness (amplitude) of each musical or sound-
effect note.
sequential file A file in which varying-length
data elements are recorded end to end, with delim-
iting characters placed between each element. To
find a particular element, you must read the whole
file up to that element.
serial The transfer of data characters one bit at a
time, sequentially, using a single electrical path.
Serial ATA See SATA.
Serial Attached SCSI (SAS) A high-speed serial
implementation of SCSI adopted in 2003, SAS com-
bines backward compatibility with SATA drives, a
current performance of 300MBps, and future
improvements to data rates up to 1,200MBps.
serial mouse A mouse designed to connect to a
computer’s serial port.
serial port An I/O connector used to connect to
serial devices. See also RS-232.
server A computer in a network that enables
resources such as files and printers to be shared by
multiple users.
Appendix A
24_0789736977_AppA.qxd 8/15/07 9:24 AM Page 63