Specifications

5
KVM Buyer’s Guide
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KVM Glossary
Bandwidth — The capacity of a device to carry
high-frequency signals through it. A device with
higher bandwidth will pass clearer and higher
resolution video. The horizontal resolution multiplied
by the vertical resolution multiplied by the frame rate
gives the approximate frequency of the pixel clock.
The bandwidth of the video is one half of the pixel
clock.
Boot — The start-up sequence of a computer.
During this time, the computer attempts to detect
the keyboard-video-mouse. A KVM switch should
emulate the KVM signals so the computer boots
up normally.
Bus Expansion — A method of interconnecting
KVM switches with multiple video buses, which go
to all switches. Any switch can connect a computer
to a video bus output or can connect a video bus
input to a user port. Each switch has a dedicated
input bus port and output bus port. The bus output
of one switch is connected to the bus input of the
next switch.
Cascading — A method of interconnecting KVM
switches by connecting the computer port of several
other KVM switches.
CAT5 — Category 5 UTP cable is usually used
for connecting LANs. It is comprised of two to four
twisted pairs of copper wire terminated by RJ-45
connectors. ServSwitch KVM extenders use this
cabling to carry video and data up to 1000 feet.
Converters — Devices that convert KVM signals
from one type of platform to KVM signals for another
type of platform, for example from PC to Sun
®
.
DVI (Digital Visual Interface) — A high-
performance interface between a computer and
a display device that uses transition-minimized
differential signaling (TMDS) for improved video
signal accuracy. DVI-D is a digital-only connector;
DVI-I integrates both digital and analog connections.
Emulation — The intelligence in a switch that
imitates (emulates) signals that enable a computer
to think it is attached directly to a keyboard-video-
mouse. (See Boot.)
Ethernet — A local area network (LAN)
developed by Xerox
®
, Digital Equipment Corp., and
Intel
®
, and now recognized as the industry standard.
Ethernet connects up to 1024 nodes at 10 MHz,
100 MHz, or 1-Gigabit speeds, over UTP, coax, and
fiber optic cable.
HDMI (High-Definition Multimedia
Interface) — This is the first digital interface to
combine uncompressed high-definition video,
multichannel audio, and intelligent format and
command data in a single cable. Use to connect
audio/video equipment over a single cable. Supports
standard, enhanced, and high-definition video. Has
a bandwidth of up to 5 Gigabytes so it supports all
HDTV standards and has bandwidth to spare for
future applications.
Flash Memory — A memory chip that holds its
content without power but must be erased in fixed
blocks rather than in single bytes. Flash memory
provides a way to change or upgrade product
functionality by sending data to change its internal
firmware.
IP (Internet Protocol) — The protocol used in
gateways to connect networks at the OSI Network
Glossary of KVM terms
Level (Layer 3) and above. IP routes a message across
networks.
Keyboard Mode — A standard PS/2
®
keyboard
can operate in Mode 1, Mode 2, or Mode 3. Mode 2
is used by the majority of PCs. Mode 1 was formerly
used by IBM
®
but is now obsolete; Mode 3 is
common for UNIX
®
workstations.
KVM — Stands for keyboard, video, mouse.
May refer to physical KVM or to the corresponding
computer ports.
KVM Extenders — Enable you to increase the
distance between the KVM and CPU or the KVM
and the switch. KVM extenders convert KVM signals
to travel over CATx UTP or single- or multimode fiber
optic cable. Distances range from 75 feet (CAT5 UTP)
to up to 6.2 miles (fiber optic single-mode).
KVM Sharing — Access to a single computer
by more than one user. Access can be controlled by
keyboard command or by timer.
KVM Switches — Connects one or more
keyboard, monitor, and mouse sets to two or more
CPUs. Users can switch via front-panel switches or
keyboard commands.
Multiplatform — Able to run more than one
type of operating system.
Non-blocking Access — A user on a matrix
switch that can connect to any computer without
restriction; this user has exclusive use of the video bus.
On-Screen Display (OSD) — For a KVM switch,
an OSD enables users to configure and control the
switch using a visual computer interface, and displays
information regarding which computer is currently
connected.
Platform — Operating system. Platforms include
PC, Sun, Apple
®
(Mac
®
), and UNIX workstations.
Port — A physical interface on a device, which
goes to a connector.
PS/2 — The keyboard and mouse standard by
IBM that was the industry standard on most PCs
and UNIX workstations. PS/2 keyboards and mice
have 6-pin mini DIN connectors.
Resolution — Number of pixels displayed
horizontally and verically on a video monitor; value
determines the sharpness of the image.
Scan Rate — The time interval that a KVM
switch takes to switch between ports. Usually a
programmable value (15 seconds, 30 seconds),
and can be enabled or disabled.
Server Access Module (SAM) — Dongle-type
device that connects CATx cable to KVM interface
connectors.
Single-User — A KVM switch with only one
point of KVM access to attached CPUs or servers.
USB (Universal Serial Bus) — Serial 4-wire bus
architecture for peripheral I/O ports, that autosenses
up to 127 peripherals at a distance of 5 meters (16.4
ft.). Version 1.1 supports 1.5- and 12-Mbps data rates.
Version 2.0 is backward compatible with Version 1.1
speeds and also supports 480-Mbps data rates.
User — A KVM workstation attached to a KVM
switch; it receives video and sends keyboard and
mouse information. Can also refer to the port on the
KVM switch or the person accessing the workstation.