Com21 Demonstrates `Wire Speed' DOCSIS Cable Modem.

ANAHEIM, Calif.--(BUSINESS WIRE)--Dec. 2, 1998--Com21, Inc. (Nasdaq:CMTO) announced today that it is demonstrating its new DOCSIS-compatible cable modem capable of transferring data at the maximum possible rate, commonly known as "wire speed."

In benchmark results published today, Com21 has demonstrated that it can filter and forward downstream packets at a rate of 14,880 packets per second, the maximum rate through a DOCSIS cable modem. It will be showing the DOCSIS cable modem at its booth 4258 at the Western Show.

"We designed an ASIC hardware packet accelerator to give us the fastest DOCSIS cable modem. Other competitors don't have special hardware and their performance suffers," said Buck Gee, vice president of marketing at Com21, "We believe that cable customers are smart, will shop around for DOCSIS cable modems, and won't accept slow products."

A cable modem receives all downstream data and must examine all data packets received, discarding all data intended for others and passing relevant data to the PC user. The rates that a cable modem can filter (examine) and forward (pass through) data packets are key performance measurements of networking devices such as routers or cable modems.

The maximum downstream packet forwarding rate supported by a 10Mbps Ethernet device such as a DOCSIS cable modem is 14,880 packets/second. This rate is achieved by transmitting a continuous stream of 64 byte packets and is commonly known as Ethernet "wire speed". If a cable modem cannot run at "wire speed" and cannot filter packets faster than it receives them, it will begin to drop packets and degrade data throughput.

About Com21

Com21 is a leading global provider of cable modem technology for delivering high-speed Internet access over CATV systems. The company enables cable operators and service providers with the abilities to provide high-speed, cost-effective Internet access to corporate telecommuters, small businesses, home offices and residential users. Founded in 1992 and completing its initial public offering in May of 1998, its stock is publicly traded on NASDAQ under the symbol CMTO. Com21 is headquartered in Milpitas. For more information, visit the Com21 web site at www.com21.com.

This press release contains forward-looking information within the meaning of the Securities Exchange Act of 1934, and is subject to the safe harbors created by those sections. These forward-looking statements include statements related to Com21, Inc.'s ability to deploy new technology and meet customer and market requirements. Actual results may differ because of numerous technology, development, and market conditions, operational capabilities, and competitive measures. The matters discussed in this press release should also be read in conjunction with risks and uncertainties described in Com21's filings with Securities and Exchange Commission (SEC). In particular, see the risk factors described in Com21's Final Prospectus for the Company's initial public offering dated May 21, 1998 and the Company's most recent 10Q dated November 3, 1998. Com21 assumes no obligation to update the forward-looking information contained in this press release.