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Black Box Explains...UARTs and PCI buses.

Universal Asynchronous Receiver/Transmitters UARTs are designed to convert sync data from a PC bus to an async format that external I/O devices such as printers or modems use. UARTs insert... more/see it nowor remove start bits, stop bits, and parity bits in the data stream as needed by the attached PC or peripheral. They can provide maximum throughput to your high-performance peripherals without slowing down your CPU.

In the early years of PCs and single-application operating systems, UARTs interfaced directly between the CPU bus and external RS-232 I/O devices. Early UARTs did not contain any type of buffer because PCs only performed one task at a time and both PCs and peripherals were slow.

With the advent of faster PCs, higher-speed modems, and multitasking operating systems, buffering (RAM or memory) was added so that UARTs could handle more data. The first buffered UART was the 16550 UART, which incorporates a 16-byte FIFO (First In First Out) buffer and can support sustained data-transfer rates up to 115.2 kbps.

The 16650 UART features a 32-byte FIFO and can handle sustained baud rates of 460.8 kbps. Burst data rates of up to 921.6 kbps have even been achieved in laboratory tests.

The 16750 UART has a 64-byte FIFO. It also features sustained baud rates of 460.8 kbps but delivers better performance because of its larger buffer.

Used in newer PCI cards, the 16850 UART has a 128-byte FIFO buffer for each port. It features sustained baud rates of 460.8 kbps.

The Peripheral Component Interconnect (PCI®) Bus enhances both speed and throughput. PCI Local Bus is a high-performance bus that provides a processor-independent data path between the CPU and high-speed peripherals. PCI is a robust interconnect interface designed specifically to accommodate multiple high-performance peripherals for graphics, full-motion video, SCSI, and LANs.

A Universal PCI (uPCI) card has connectors that work with both a newer 3.3-V power supply and motherboard and with older 5.5-V versions. collapse


Black Box Explains...NEBS Level 3.

Network Equipment Building System (NEBS) standards set requirements for telco equipment. The standards are maintained by Telcordia Technologies, Inc., formerly Bellcore. Bellcore Special Report, SR-3580 defines three distinct functional levels... more/see it nowof NEBS compliance. The third of these levels, NEBS Level 3, is the most stringent, certifying carrier-class equipment intended for long-term use in variable environments.

NEBS Level 3 certifies that a piece of equipment can be safely used in an extreme environment. To become certified at NEBS Level 3, a device must meet strict physical, electrical, and environmental requirements to prove it will operate safely and reliably in extreme conditions. It must pass a series of tests that include extreme heat, humidity, fire, earthquakes (Zone 4), light, and noise. collapse


Black Box Explains…Before the ServSwitch.

Before the introduction of the ServSwitch, accessing more than one CPU from a single keyboard, monitor, and mouse was problematic. Keyboard/video (KV) or keyboard/video/mouse (KVM) switches frequently caused CPUs to... more/see it nowlock up because the CPUs weren’t always receiving the signals they expected from the keyboard. Managing server farms was a nuisance because either each server needed its own keyboard, monitor, and mouse, it or was subject to frequent rebooting if used with a KVM switch.

The BLACK BOX® ServSwitch™ KVM Switch changed all that. The ServSwitch enables frequent switching between multiple CPUs (up to 3000!) without the danger of CPUs locking up. That’s because the ServSwitch is built with sophisticated circuitry that keeps feeding each CPU the keyboard and mouse signals it expects.

So why are we still selling preServSwitch keyboard/video switches? The Number 1 reason is many of our customers have preinstalled applications in which these switches are specified, so we keep stocking them as a service. Another reason is there is still some call for these switches for applications in which only limited switching is required.

However, for most KVM applications, we recommend a BLACK BOX® ServSwitch™ KVM Switch as the most reliable switching solution. We have ServSwitch products and accessories for everything from a simple desktop application to managing all the servers in your enterprise network.

Simplify and save with BLACK BOX® ServSwitch™ Technology! collapse


Black Box Explains...Link loss.

Media converters solve the problem of connecting different media types in mixed-media networks. In order to comply with IEEE standards, they implement IEEE data-encoding rules and the Link Integrity Test.

For... more/see it nowa twisted-pair segment, a link is a signal sent by the converters when the cable is in use. If no Link Integrity Test signal is received, the connected device assumes that the link is lost.

With fiber cable, a connected device checks a line by monitoring the Link Integrity Test signal from the converter and the power of the light being received. If the light’s power drops below a certain threshold, the link is lost. In either case, link loss usually results from a broken cable, which is the cause of approximately 70% of all LAN problems.

Link loss is often indicated by an LED on a connected network device. You can also monitor a link with network-management software, such as SNMP, which sends a TRAP (alert) to the management workstation when the link is lost.

Media converters actually function as two separate Multistation Access Units (MAUs). For example, one monitor is a twisted-pair segment and one monitor is a fiber segment. If a fiber cable is broken and the link is lost, a network manager on the twisted-pair end won’t know there’s a problem until users on the fiber side report it.

To solve this problem, Black Box® Modular Media Converters feature a unique Link-Loss capability. This enables the link status on one segment to reflect the link status of the other segment. So if the link is lost on the fiber side, the link is disabled on the UTP segment as well. And the converters will send an SNMP TRAP indicating the loss of link to the management workstation. collapse


Black Box Explains...Media converters.



Media converters interconnect different cable types such as twisted pair, fiber, and coax within an existing network. They are often used to connect newer Ethernet equipment to legacy cabling.... more/see it nowThey can also be used in pairs to insert a fiber segment into copper networks to increase cabling distances and enhance immunity to electromagnetic interference (EMI).


Traditional media converters are purely Layer 1 devices that only convert electrical signals and physical media. They don’t do anything to the data coming through the link so they’re totally transparent to data. These converters have two ports—one port for each media type. Layer 1 media converters only operate at one speed and cannot, for instance, support both 10-Mbps and 100-Mbps Ethernet.


Some media converters are more advanced Layer 2 Ethernet devices that, like traditional media converters, provide Layer 1 electrical and physical conversion. But, unlike traditional media converters, they also provide Layer 2 services—in other words, they’re really switches. This kind of media converter often has more than two ports, enabling you to, for instance, extend two or more copper links across a single fiber link. They also often feature autosensing ports on the copper side, making them useful for linking segments operating at different speeds.


Media converters are available in standalone models that convert between two different media types and in chassis-based models that connect many different media types in a single housing.




Rent an apartment

Standalone converters convert between two media. But, like a small apartment, they can be outgrown. Consider your current and future applications before selecting a media converter. Standalone converters are available in many configurations, including 10BASE-T to multimode or single-mode fiber, 10BASE-T to Thin coax (ThinNet), 10BASE-T to thick coax (standard Ethernet), CDDI to FDDI, and Thin coax to fiber. 100BASE-T and 100BASE-FX models that connect UTP to single- or multimode fiber are also available. With the development of Gigabit Ethernet (1000 Mbps), media converters have been created to make the transition to high-speed networks easier.




...or buy a house.

Chassis-based or modular media converters are normally rackmountable and have slots that house media converter modules. Like a well-planned house, the chassis gives you room to grow. These are used when many Ethernet segments of different media types need to be connected in a central location. Modules are available for the same conversions performed by the standalone converters, and 10BASE-T, 100BASE-TX, 100BASE-FX, and Gigabit modules may also be mixed.

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Black Box Explains...Ceramic and composite ferrules.

Cables manufactured with ceramic ferrules are ideal for mission-critical applications or connections that are changed frequently. These cables are high quality and typically have a very long life. Ceramic ferrules... more/see it noware more precisely molded and fit closer to the fiber than their composite counterparts, which gives them a lower optical loss.

On the other hand, cables with composite ferrules are ideal for less critical applications or connections that won’t be changed frequently. Composite ferrule cables are characterized by low loss, good quality, and long life. collapse


Black Box Explains... Coax cables for ServSwitch products.

What’s the difference between standard and coax cables for ServSwitch™ products? Performance! Coax cables are made with premium-gauge wire, so they can be made in longer lengths. That means you... more/see it nowcan move your workstation up to 100 feet (30.4 m) from your ServSwitch. Plus coax cables have even more shielding to maintain the signal quality and strength you need. If you require high-resolution video or long distances, this is the cable you need! collapse


Black Box Explains...SCSI Ultra2 and LVD (Low-Voltage Differential).

Small Computer Systems Interface (SCSI), pronounced “scuzzy,” has been the dominant technology used to connect computers and high-speed peripherals since the 1980s. SCSI technology is constantly evolving to accommodate increased... more/see it nowbandwidth needs. One of the more recent developments is Ultra2 SCSI.

Because Ultra2 SCSI is backward compatible, it works with all legacy equipment. Ultra2 doubles the possible bandwidth on the bus from 40 to 80 MBps! Just as importantly, Ultra2 supports distances up to 12 meters (39.3 ft.) for a multiple-device configuration. Ultra2 uses Low-voltage Differential (LVD) techniques to transfer data at faster rates with fewer errors. Don’t confuse Ultra2 with LVD. Ultra2 is a data-transfer method; LVD is the signaling technique used to transfer the data.

Cables are very important when designing or upgrading a system to take advantage of Ultra2 SCSI. Cables and connectors must be of high quality and they should come from a reputable manufacturer to prevent crosstalk and minimize signal radiation. BLACK BOX® Ultra2 LVD cables are constructed of the finest-quality components to provide your system with the maximum protection and highest possible data-transfer rates. collapse


Black Box Explains...Connecting peripherals with USB.

Before Universal Serial Bus (USB), adding peripherals required skill. You had to open your computer to install a card, set DIP switches, and make IRQ settings. Now you can connect... more/see it nowdigital joysticks, scanners, speakers, cameras, or PC telephones to your computer instantly. With USB, anyone can make the connection because everything is automatic!

Because USB connections are hot-swappable, you can attach or remove peripherals without shutting down your computer. Also, USB hubs have additional ports that enable you to daisychain multiple devices together. More than 800 leading PC, peripheral, and software manufacturers support USB. collapse


Black Box Explains...How MicroRACK Cards fit together.

Slide a function card into the front of the rack. Then slide a connector card in from the back. The rest is simple. Just press the cards together firmly inside... more/see it nowthe rack to seat the connectors.

Changing systems? It’s easy to change to a different connector card. Just contact us, and we’ll find the right connection for you.

Add a hot-swappable power supply (AC for normal operation, VDC for battery-powered sites), and you’re up and running. collapse

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