Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site ecsvax.UUCP Path: utzoo!watmath!clyde!bonnie!akgua!mcnc!ecsvax!hes From: hes@ecsvax.UUCP (Henry Schaffer) Newsgroups: net.dcom Subject: FASTLINK (tm) "10,000 bps or faster" modem Message-ID: <720@ecsvax.UUCP> Date: Fri, 8-Nov-85 14:49:47 EST Article-I.D.: ecsvax.720 Posted: Fri Nov 8 14:49:47 1985 Date-Received: Wed, 13-Nov-85 07:40:39 EST Distribution: net Organization: NC State Univ. Lines: 40 I got the glossy 4 page brochure from Digital Communications Associates, Inc. (the IRMA people) about their FASTLINK (tm) 10,000 bps modem. It also has 300 and 1200 compatibility, but I thought people might be interested in some of the "fast" features. "Data transmission at 10,000 bps or faster." N1 "Asynchronous dial-up connection." "Automatic error detection and correction." N2 N1- inside it says "Poor quality lines may result in lower transmisssion speeds." N2- Correction is done by the sending modem adding a CRC to each packet, and then, "If the receiving modem detects an error, it requests a retransmission to insure error-free transmission." This modem sends out a bunch ("hundreds") of tones, decides which ones are acceptable for use, and uses these. When the S/N ratio is bad, fewer bits are encoded on each tone, and this is varied incrementally every few milliseconds. Also, while this modem is full duplex, it adaptively varies how much of the transmission capacity is allocated to each direction. (So I imagine that the "10,000 bps or faster" speed is reached with nearly all the data going in one direction.) They call this a "Packetized Ensemble Modem". It comes bundled with a special version of Crosstalk (r) for IBM PC/clones. The modem has a superset of Hayes commands, and gives access to its registers containing "phone line characteristics such as signal-to-noise ratio, number of retransmitted packets, bits per packet, and frequency offset." It is not clear how big the packets are, two places say they vary, and one place says they don't. No mention is made of performance in a character echo environment. All this fancy stuff is done by "multi- processor power, capable of handling over 7" MIPS. The company is at 1000 Alderman Dr., Alpharetta, GA 30201 (404)442-4000 and the list price of the stand-alone version is $2395. (The PC card version is $400 less.) --henry schaffer n c state univ Standard Disclaimer - and I've never even seen one of them (the modems).