Telebit was a modem manufacturer known for its high-speed TrailBlazer series of modems. The TrailBlazer used a proprietary modulation scheme called PEP that allowed speeds over 9600 bits/s and was highly reliable even on poor phone lines. Telebit also produced the NetBlazer, one of the first internet dial-up routers. While Telebit introduced newer models with V.32 and V.32bis standards, they struggled to compete against lower cost options from other manufacturers using chipsets from Rockwell.

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Telebit
From Wikipedia, the free encyclopedia
Telebit was a US­based modem manufacturer, known for their TrailBlazer series of
high­speed modems. One of the first modems to routinely exceed 9600 bit/s speeds,
the TrailBlazer used a proprietary modulation scheme that proved highly resilient to
interference, earning the product an almost legendary reputation for reliability despite
mediocre (or worse) line quality. They were particularly common in Unix installations
in the 1980s and 1990s.
Contents
1 Startup
2 PEP and the TrailBlazer
3 NetBlazer
4 Increasing speeds
5 The Octocom merger and the FastBlazer V.34 modem
6 Next phase
7 Legacy
8 Models
9 References
10 External links
Startup
Telebit was founded by Paul Baran, one of the inventors of the packet switching
networking concept. Baran had recently started a networking company known as
Packet Technologies on Bubb Road in Cupertino, California, which was working on
systems for interactive television. While working there, he hit on the idea for a new
way to implement high­speed modems, and started Telebit across the street. Packet

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T2000 Dialing, negotiating and
communicating
The host modem negotiates
with the client. It is possible to
hear the modem negotiation,
the measurement of line
quality, and the constant
switching of the deirection of
transmission, since no data is
being transferred.
Problems playing this file? See media
help.
Technologies was a major beta customer for Telebit in late 1985. Packet Technologies
later failed, and several of their employees were folded into Telebit, while most of the
others formed StrataCom, makers of the first Asynchronous Transfer Mode (ATM)
switches.
PEP and the TrailBlazer
In contrast to then­existing ITU
Telecommunication Standardization Sector
(ITU­T) V­series protocols, such as the
common 2400 bit/s V.22bis, the
TrailBlazers' proprietary Packetized
Ensemble Protocol (PEP) modulation
employed a large number (initially up to
512) of closely spaced carrier frequencies,
each modulated at 6 baud, encoding 0, 2, 4
or 6 bits per interval. Under favorable
conditions, the devices could reach data
rates of 6 baud x 6 bits­per­baud x 512
carriers = 18432 bits per second. If a
particular carrier was distorted, attenuated or interfered with, it could be turned off,
allowing the data rate to degrade gracefully with decreasing line quality.
Most modems of the era were set up with both channels with equal speed (full
duplex), or, in the case where data was primarily sent in one direction, with a single
high speed channel (half duplex). The TrailBlazer instead allowed any one of its 512
channels to be assigned to transfer data in either direction, a technique they termed
"adaptive duplex". The modem was designed to use most of the bandwidth in a single
direction, with a relatively low speed reverse channel. The modems at the two ends of
the connection would negotiate line turnarounds, reversing the directions of the high­
speed and low­speed channels, based on the amount of data queued for transmission
in each modem.
While this adaptive duplex scheme was able to send large files quickly, for users
accustomed to having the distant computer echo characters, the delay associated with
having the DSPs take turns using the bandwidth tended make interactive typing
difficult, as there could be as much as a second and a half delay for a single character
0:00 MENU

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echo. This also caused problems for file transfer protocols, e.g., UUCP 'g' or Kermit,
where a small packet of data was sent by one computer, followed by a wait for
acknowledgment from the receiver ("send and wait").
The TrailBlazer addressed this problem through a technique known as "protocol
spoofing". When the local computer sent a packet to the modem for transmission, the
modem's controller immediately sent an ACK message, generated locally. This fooled
the computer into thinking the packet had already reached the far end, prompting it to
send another packet. The error correction normally being applied in the protocol was
instead handled using a proprietary replacement protocol operating on top of the MNP
error­correcting protocols to talk to the remote modem. In general, spoofing worked
well with any protocol that used small packets, and thus generated lots of ACK
messages; initially UUCP, and support for XModem and Kermit followed.
Support for these features did not come easily; the TrailBlazer Plus, for instance, used
a Motorola 68000 to drive its electronics. This meant that the TrailBlazers were
generally very expensive. However, its spoofing ability made the TrailBlazer modems
extremely popular in the Unix world, as it could dramatically improve UUCP
throughput, even at low connection speeds on very noisy lines. Improvements of over
7 times faster than a 2400 bit/s modem were not uncommon. Sites that required long­
distance telephone calls to exchange UUCP mail could pay for the price of a
TrailBlazer in long­distance savings fairly quickly.
The Trailblazers also introduced an extensive set of commands for setting up its
various options. While most of the simple commands were based on the Hayes
command set, like dialing a number or hanging up a phone, their proprietary
capabilities were supported by proprietary commands and syntax. Most of these took
the form of register=value pairs, leading to extremely long and almost
undecipherable setup strings.
In 1988 Telebit added the T1000, essentially a TrailBlazer limited to a lower­speed
9600 bit/s version of PEP, remaining compatible at that speed with existing
TrailBlazers. The T2000 added support for synchronous communications, typically
used between mainframe computers. The original TrailBlazer, T1000 and T2000 were
backwards­compatible with the 2400 bit/s V.22bis standard, allowing them to connect
with what was then the most common modem speed when talking to other brands of
modems.

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Telebit T2500 from about 1989
NetBlazer
Another Telebit product was the first on­demand Internet dialup router, the
NetBlazer. The product was developed by a team led by Mike Ballard, formerly of
Packet, who eventually became Telebit's CEO in 1986, and president in 1992.
The original NetBlazer was a standard PC with a serial card connected to user
supplied external modems by serial cables. Later smaller versions, the PN and STi,
were offered which consisted of a small­form­factor PC combined with custom
software and one of a variety of modems or other connection systems (ISDN, etc.)
combined into a large modem­like box. Administrators connected to it via Ethernet,
which was also used for maintenance commands and setup.
In its first release the NetBlazer software supported TCP/IP using SLIP, but a later
upgrade added Point­to­Point Protocol (PPP) and support for IPX and AppleTalk.[1]
The protocol stack was a commercially licensed version of KA9Q. Later versions of
the hardware switched from the Intel 80386 to a low­cost microcontroller version of
the Motorola 68030, the MC68EN360.
Increasing speeds
Telebit had their initial public offering in
April 1990, which raised about $20.2
million. It traded on NASDAQ with the
symbol TBIT.[2]
The first multi­company standard for 9600
bit/s dialup modems was V.32, introduced in
1989. Initially V.32 modems were very
expensive, but Rockwell introduced
modules, and eventually entire chipsets, that brought the prices down. Telebit first
offered V.32 support in the T2500, which used the Trailblazer/T2000 hardware with
the addition of the Rockwell V.32 modem module. A version without PEP support
was offered as the T1500. The later T1600 had basically the same feature set as the
T1500, but used Telebit's own V.32 implementation rather than the Rockwell module,

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resulting in reduced production cost and better performance. Both the T1500 and
T1600 had list prices over $1000; at the time a 1st tier product from Hayes or U.S.
Robotics (USR) generally cost about $700.
The V.32bis standard, increasing the bit rate to 14,400 bit/s, was introduced in 1991.
In this case Rockwell quickly released a V.32bis chipset, appearing on the market so
rapidly that Rockwell­based systems generally pre­dated implementations from other
companies. Rockwell also aggressively priced the V.32bis product line, allowing
modems based on them to sell at price points around $300, the point formerly held by
2400 bit/s models that offered no error correction or compression, nor fax capabilities.
All of the 1st tier companies had serious difficulties adapting to a market that was
now filled with low­cost modems with similar or better performance and features than
their own high­end models.
Telebit started slipping in terms of relative performance, while still trying to sell their
products at their traditional high price points. They finally introduced the T3000 with
V.32bis but without PEP, though a PEP upgrade was planned. Instead, Telebit "re­
released" it in early 1994 as the $1,099 WorldBlazer model; essentially a T3000 with
the new 23,000 bit/s TurboPEP mode. An upgrade from the T3000 to WorldBlazer
was sold, consisting of two firmware ROMs and a PAL chip.
There were some design studies of a possible full­duplex PEP using echo cancellation
(as is used in V.32), and this technology was proposed to the CCITT (now known as
the ITU­T) for possible adoption as the V.fast modem standard. However, more
conventional modem technology was chosen and standardized as V.34. Telebit
deemed full­duplex PEP to require more engineering effort than was justified by the
shrinking market for PEP modems, and never introduced this feature.
The Octocom merger and the FastBlazer V.34 modem
The CCITT moved quickly to improve on V.32bis, and by 1993 it was clear that the
ratification process for their new 28,800 bit/s V.34 standard was going to be finalized
in 1994. Companies lined up to start production of new V.34 designs, some going so
far to introduce models based on interim standards, such as V.FC.
Telebit's modem engineering team developed a plan for a V.34 modem, but the
executive staff believed that it was important to get a product to market more quickly.
To that end, they began looking for other modem companies to acquire, and in

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January 1993 announce that Telebit would acquire Octocom Systems, a small
privately held modem company in Massachusetts. Octocom had a V.34 modem in
development which was expected to be ready for shipment quickly. Almost all
modem engineering activities at Telebit's California offices ceased, though NetBlazer
engineering continued to be based in California until the end of 1995.
The Telebit FastBlazer 8840 V.34 modem was introduced in May 1994. When the
FastBlazer was first introduced it did not include V.34 support, with management
stating that they couldn't do so because the standard was not yet ratified. Although this
was true (for one month anyway, it was ratified in June), the FastBlazer did not ship
with an interim standard either; even AT&T's largely ignored 19,200 bit/s V.32terbo
would only be available as a post­release upgrade in July, there were no plans to
support the widespread V.FC at all, and no date was set for full V.34 support other
than "two or three months".
Making matters worse, the FastBlazer didn't include fax support. While Telebit stated
that an upgrade to add this would be available, they also stated they would be
charging for it. Nor would the FastBlazer support PEP, which, although by then a
minor consideration for most potential buyers, was still a differentiator for Telebit's
existing installed base. For sites with a Telebit modem on at least one end of a link, a
PEP­capable upgrade might be worthwhile. Without PEP, the FastBlazer had
essentially no advantage over any other V.34 modem.
All this for an introductory price of $1,399, when V.32bis faxmodems were available
for $200 or less, and industrial­quality V.34 designs were soon available for under
$500.
It took seven months before Telebit introduced V.34 support in January 1995, also
releasing the $399 TeleBlazer "low­end" model at the same time. By this point even
long­time supporters were publicly pooh­poohing the company on the UseNet, the
medium that originally drove the widespread adoption of the TrailBlazer.
Next phase
Late in 1993 Telebit completed their merger with Octocom, the idea being to use
Octocom's Chelmsford, Massachusetts manufacturing capability headed by veteran
executive Bryan Holley, as executive vice president of worldwide operations,
downsizing the existing Sunnyvale office to become a NetBlazer development site

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under the supervision James Norrod. The Sunnyvale facility was closed to reduce
costs. Higher than expected operating costs resulted in stagnation with the
development of new products. The difficult integration of the Sunnyvale operation
into the corporate Chelmsford, MA headquarters was fraught with more difficulties
than those of finance and marketing. Both companies had a staunch and loyal
following of customers and the surprise that the acquiring Telebit gaining Octocom
would, in effect, flip around as Octocom essentially absorbing Telebit left some
customers and many non­surviving post­merger employees not surprisingly bitter. By
March 1996 the company had exhausted its line of credit, reducing cash by $3.2
million on revenues of $12.7 million in the quarter.[2]
In July 1996 Telebit was acquired by Cisco Systems for $200 million, primarily for
their channelized T1 digital­modem technology: (modem ISDN channel aggregation
(MICA)). Telebit management convinced Cisco to spin off the company including all
existing product families as well as a paid­up license for the use of MICA in future
products developed by the spinoff to one of the existing management team (James D.
Norrod) to become Telebit Incorporated and based in Chelmsford.[3][4][5]
In August 1997 Telebit merged with ITK Telekommunikation, based in Dortmund
Germany.[6] Telebit executive vice president Bryan Holley was named president and
chief executive officer for the new ITK Telecommunications, Inc. under which
leading the newly minted ITK through further M&A activity culminating with the
combined company being acquired in July 1998 by Digi International, makers of the
DigiBoard multi­port serial card for PCs.
Legacy
While the Trailblazers have generally been displaced by modems implementing the
higher­rate V.34/V.90 series standards, and although they have been out of production
since the mid­1990s, many TrailBlazers continue to be in operation to this date, and
repair services are still available.
Orthogonal frequency­division multiplexing (OFDM), which is used in both the ITU
Asymmetric Digital Subscriber Line (ADSL) and IEEE 802.11 Wireless LAN
standards, has some of its roots in the Packet Ensemble Protocol. In particular, these
protocols reuse PEP's concept of carrying a single data link over many lower rate
[frequency­division multiplexing]] sub­carriers.

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German version of T2000,
T2500 and T3000 (with
Turbo­PEP)
In 1995, a Silicon Valley engineer sent a Worldblazer to an NGO in Somalia, which
promptly put it to work connecting that remote country to the Internet, at first by
UUCP, then by other means.
Models

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Model Year Capabilities
Trailblazer 1985 Original model, approximately 18,000 bit/s
Trailblazer+ ? performance improvement, over 19,000 bit/s
T1000 1988 lower­cost model limited to 9600 bit/s
Cellblazer 1989 for use with cellphones
T2000 ? synchronous link support
T2500 ?
T2000 + V.32 (9600 bit/s) support added based on Rockwell
module
T1500 ? V.32 (9600 bit/s) without PEP, Rockwell based
T1600 ? V.32, Telebit­internal implementation
T3000 ? V.32bis(14400 bit/s) and fax support
WorldBlazer 1994 T3000 with TurboPEP and, later, fax
FastBlazer 1994 V.34 (28800 bit/s)
TeleBlazer 1995 "low cost" V.34
QBlazer 1991 V.32 (9600 bit/s) battery­powered portable modem
QBlazer+ ? V.32bis (14400 bit/s) version of the QBlazer
NetBlazer ? Ethernet­connected on­demand SLIP and PPP router
References
1. ^ "NetBlazer Product Line Overview"
(http://web.archive.org/web/19971017051509/http://www.telebit.com/ProductS/nbmtrx.ht
ml). April 9, 1996. Archived from the original
(http://www.telebit.com/ProductS/nbmtrx.html) on October 17, 1997. Retrieved
October 8, 2013.
2. ^ a b "Quarterly Report for the Quarter Ended March 30, 1996"
(http://www.sec.gov/Archives/edgar/data/744550/0000903893­96­000224.txt). Form 10­
Q. US Securities and Exchange Commission. May 13, 1996. Retrieved October 8, 2013.
3. ^ "Telebit/Cisco Agreement"
(http://web.archive.org/web/19970607012842/http://www.telebit.com/CompanY/letter1.ht

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Wikimedia Commons
has media related to
Modems (Telebit).
ml). Telebit, Incorporated. Archived from the original
(http://www.telebit.com/CompanY/letter1.html) on June 7, 1997. Retrieved October 8,
2013.
4. ^ "Quarterly Report for the Quarter Ended June 29, 1996"
(http://www.sec.gov/Archives/edgar/data/744550/0000903893­96­000579.txt). Form 10­
Q. US Securities and Exchange Commission. August 13, 1996. Retrieved October 8,
2013.
5. ^ "Transaction Statement: Telebit Corporation, Telebit (Newco) Inc. and Proxy Materials"
(http://www.sec.gov/Archives/edgar/data/744550/0000903893­96­000752.txt). Schedule
13E­3. US Securities and Exchange Commission. September 18, 1996. Retrieved
October 8, 2013.
6. ^ "Telebit Incorporated and ITK Completion Merger"
(http://web.archive.org/web/19971017045836/http://www.telebit.com/NewS/itkmer~1.ht
ml). Press release. Telebit, Incorporated. August 20, 1997. Archived from the original
(http://www.telebit.com/NewS/itkmer~1.html) on October 71, 1997. Retrieved October 8,
2013. Check date values in: |archivedate= (help)
External links
A Brief History of Telebit
(http://www.brouhaha.com/~eric/personal/telebit.html)
Telebit Product Repair (http://www.ntsnh.com/telebitproduct.htm)
UUCP 'g' Protocol (http://www.faqs.org/faqs/uucp­internals/section­7.html)
Retrieved from "http://en.wikipedia.org/w/index.php?
title=Telebit&oldid=650590216"
Categories: Telecommunications equipment vendors
Defunct networking companies Modems Cisco Systems acquisitions
Computer companies of the United States

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