Product guide

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Appendix C Glossary
ECC RAM: Error Checking and Correcting Memory. Advanced
type of memory that can find and correct certain types of
single-bit memory errors, providing greater data integrity.
Advanced ECC can correct some double-bit errors.
EDRAM: Enhanced Dynamic Random Access Memory. Like
cached DRAM, enhanced DRAM also incorporates an on-chip
SRAM cache in an attempt to improve on the average access
time. By improving the DRAM's performance (with the reduction
of parasitic capacitance and an increase in transistor gain) to
35ns, and combining it with a 2Kb, 15ns SRAM cache, a DRAM
chip with a 15ns access time is created. In contrast, cached
DRAM uses a much larger 15Kb, 15ns cache and DRAM with a
much slower 70ns access time.
EDO RAM : Extended Data Out Random Access Memory. A
newer, faster type of computer memory that holds its last-
requested data in a cache after releasing it. Now becoming
standard on personal computers. EDO DRAM is almost the
same as FPM, with a slight modification that allows back-to-
back memory accesses to occur much faster.
EEPROM : Electrically Erasable Programmable Read Only
Memory. Used to store modifiable BIOS code. It retains its
contents for 10 years even with no power at all. For PCI bus
machines, EEPROM will allow you to easily upgrade as the plug
and play features are standardized.
EIDE: Extended Integrated Drive Electronics. The EIDE
specification is an enhanced version of the IDE mass storage
device interface that allows for faster transfer rates and
supports larger hard drive sizes. It supports data rates of
between 4 and 16.6 MB (megabytes) per second, and supports
mass storage devices of up to 8.4 GB, using the logical block
addressing feature to access data faster. EIDE is sometimes
referred to as Fast ATA, or Fast IDE, which is essentially the
same standard. There are four EIDE modes defined. The most
common is Mode 3, which transfer data at a rate of 11.1 MBps
(megabytes per second). Mode 4 supports transfer rates of 16.6
MBps.
EMI: Electro-Magnetic Interference. Interference in the integrity of
a signal caused by radiation. An example is the radiation from a
fluorescent lamp, which emits a broad spectrum of
electromagnetic radiation, including radiation that may be harmful
to a signal not protected by either shielding or adequate twisting.
ESCD: Extended System Configuration Data. An area of BIOS
memory that stores configuration data on all onboard and add-in
cards.
Ethernet: IEEE-standard data link protocol that specifies how data
is placed on and retrieved from a common transmission medium.
Data is broken into packets, which are then transmitted using the
Carrier Sense Multiple Access / Collision Detect (CSMA/CD)
algorithm until they arrive at the destination without colliding with
any other. A node is either transmitting or receiving at any instant.
Bandwidth ~10 Mbps. Disk-Ethernet-Disk transfer rate with TCP /
IP is typically 30 KBps. The cable is a 50 ohm coaxial cable with
multiple shielding. Forms the underlying transport vehicle used by
several upper-level protocols, including TCP/IP and XNS.
Expansion Slot: An integrated socket on the computer's main
system circuit board allowing new capabilities to be added the
computer. The boards inserted into the expansion slots are called
expansion boards, expansion cards, add-ins, and add-ons.
Expansion slots for PCs come in two basic sizes: half-and full-
size. Half-size slots are also called 8-bit slots because they can
transfer 8 bits at a time. Full-size slots are sometimes called 16-
bit or 32-bit slots.
Failback: The process of returning control of some or all of the
same (failover) customer resources to the original server after it
has been returned to a working condition.