v.90, X2 and K56 flex

As always, there was a race to rush the next high speed protocol to market. The war was between two camps: Motorola and Lucent on one side, and US Robotics and Texas Instruments on the other. Motorola and Lucent developed a protocol called K56flex. US Robotics developed X2. Both protocols allowed modems to download data at speeds approaching 56kbps.

These modems took advantage of the pulse code modulation (PCM) used in the newer digital public telephone systems, and the near-zero loss these systems have. The idea was to transmit analog audio signals that would translate directly into specific PCM pulse-codes that the phone system could send all the way to the receiving modems at the Internet Service Provider's (ISP's) point of presence (POP). Being digital all the way out to the ISP and back means that no data is lost to line noise or digital conversion and therefore more data can be transmitted. In normal modem transmission along a system that is completely analog from end to end, or partially digital, data is lost at each point where a conversion between analog and digital occurs.

While these two protocols (X2 and K56flex) were fighting it out in the retail arena, the ITU ratified the V.90 standard. What was unique about this version of modems was that the manufacturers actually planned for the development of the V.90 standard. In the past, manufacturers would rush their own proprietary standard to market. This meant that to make things work at the highest possible speeds, you had to have the same manufacturers modem at both ends of the connection. This was often difficult to acheive. When the standard came out, it was always adopted by the modem manufacturers, and the standards have never supported the proprietary protocols. This meant that anyone who bought one of the early modems with the proprietary protocol was stuck with useless hardware.

With THIS set of modems, the manufacturers put EPROMS in the modems so that they could be flash-upgraded to the V.90 standard (and in some cases to the v.92 standard) when it came out. This was a win-win for the consumers and the modem manufacturers.

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