Path: utzoo!utgpu!water!watmath!clyde!cbosgd!mandrill!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.dcom.modems
Subject: Re: Telebit Rev 4.0 reverse channel (was: Trailblazer working on tty000?)
Summary: AMD Worldchip only for slow connects.
Message-ID: <1009@neoucom.UUCP>
Date: 14 Feb 88 01:14:32 GMT
References: <995@neoucom.UUCP> <718@ddsw1.UUCP> <577@tapa.UUCP>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 16


Apologies if I gave the impression that the Worldchip did the
highspeed magic in the TB modem.  I only mentioned it for
comparison against the Rockwell off-the-shelf chips in the other
modems.

The serious high speed FAST mode of the TB uses a Trellis coding
method, and is modulated/demoduated using an MC68000 CPU and a
General Instruments DSP chip which implement a Vitterbi (sp?)
algorithm.  The newer TB Plus models have integrated much of the
SSI / MSI functions into a Toshiba-made gate array.  Another nice
feature of the Plus model is that it includes a programming
resistor that allows one to set the transmitter level for use in
leased-line applications.

--Bill