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Date: Sun 01-Nov-1989 05:58:27 From: Unknown Subject: Modems and the NeXT I understand one of the serial connectors on the cube can be used to hook up a modem with a standard Mac cable. What do I actually have to do on the cube to use Terminal to dial out? Do I just naively say Terminal </dev/something ? Also, what became of the idea to use the DSP as a 9600-baud modem? That would save me about $500, and partially make up for the fee that I'll have to pay to purchase the cube. A modem then becomes software and, I suppose, some D-A conversion circuitry. Hmm- what about incoming data? I don't believe there is A-D circuitry in the NeXT with that kind of bandwidth. What would be the cost of producing such a device? I hear that Hayes is working on a NeXT modem. Why is there a need for a NeXT-specific product from Hayes? Would this take advantage of the DSP? Thanks, Jonathan Dubman UC Berkeley >From: dml@esl.com (Denis Lynch)
Date: Sun 01-Nov-1989 18:17:41 From: Unknown Subject: Re: Modems and the NeXT In article <1989Nov1.055827.2375@agate.berkeley.edu> dubman@ocf.berkeley.edu (Jonathan Dubman) writes: >some D-A conversion circuitry. Hmm- what about incoming data? I don't >believe there is A-D circuitry in the NeXT with that kind of bandwidth. >What would be the cost of producing such a device? > >Jonathan Dubman The NeXT has just the right A-D system. While the D-A is 16-bit 44kHz (far better than anything you'll get on the phone system -- short of digital) the A-D is an 8-bit mu-law encoded converter operating at 8kHz. This is exactly what the phone system uses to digitize phone lines. (In North America at least. Most of Europe uses A-law encoding.) Most of these chips have their own built in filters the limit the bandwidth to 300-3300Hz, which is just what the BOCs and ATT promise you. That 9600 bps modems will work under these conditions is impressive enough, but the following anecdote may amuse you. This is a true story that happened just under 4 years ago during my sojourn in industry. We were developing a combined data and voice multiplexer for T1 lines (1.544Mbps). The system was basically a data mux with voice thrown in as a real nice feature (marketing later flipped that in some contract negotiations, but that's another story). Well, we ran into some problems with the customer that was contracting to sell these things in the US. It seems that they had trouble passing 9600 modem signals through 3 tandems of voice channels with our voice compression on. With that configuration, each tandem had an A-D which produced 64kbps which was then compressed to 32kbps and send over the T1. At the other end, the 32kbps was expanded back to 64kbps and reconverted back to analog. They were doing this three times and expected no errors. To make a long story a little shorter, we finally managed to get the error rate to a acceptable level. However, it alway bothered me: why do all that to push 9.6kbps through a machine that was designed to mux data in the first place? Now just imagine all the junk that would lie between the 68030s in a couple of NeXTs running modems talking over such a network. I can hear the ghost of Edison now: Tell me again why this is better than a wire? The world's a scary place --- but it's the only one we've got. Brian L. Stuart Department of Computer Science Purdue University >From: conrad@cgl.ucsf.edu (Conrad Huang)
Date: Sun 02-Nov-1989 05:35:21 From: Unknown Subject: Re: Modems and the NeXT The Next comes with tip, which allows you to call out with a modem in a pretty painless way. just connect the modem to serial port a on the cube (its pin- compatible with the mac serial ports, so any cable that will connect your modem to a mac will connect it to serial a on the cube.Then all you have to do is edit the /etc/remote file to put in aliases for what machines to call at what phone numbers and baud rates.The man page on tip and the one on "remote" are relatively intelligible. The bottom line is that right now i am writing this from a NeXt at home, talking to a Sun at school over my $141 Zoom 2400 modem with mac cable, and to phone the broadband net "Tigernet" which the Sun is accessible through all I did was type "tip tiger" in a Terminal window. Enjoy Nick Katz >From: rheiger@ccng.waterloo.edu (Richard H. E. Eiger)
Date: Sun 02-Nov-1989 00:24:49 From: Unknown Subject: Re: Modems and the NeXT In article <1989Nov1.055827.2375@agate.berkeley.edu> dubman@ocf.berkeley.edu (Jonathan Dubman) writes: > [...] >Also, what became of the idea to use the DSP as a 9600-baud modem? That >would save me about $500, and partially make up for the fee that I'll have >to pay to purchase the cube. A modem then becomes software and, I suppose, >some D-A conversion circuitry. Hmm- what about incoming data? I don't > [...] > I would be interested in a source of these/this software too. My cube hasn't arrived yet, but I intend to do conventional datatransfer (9600 bps) and FAX over the same line. Is there any system / software supporting this. It should of course be able to accept incoming calls and decide whether it's a FAX being transmitted or a user who wants to log in. >I hear that Hayes is working on a NeXT modem. Why is there a need for >a NeXT-specific product from Hayes? Would this take advantage of the DSP? > I wonder about that too. Many thanks. Richard (rheiger@ccng.waterloo.edu) >From: madler@tybalt.caltech.edu (Mark Adler)
Date: Sun 03-Nov-1989 18:47:00 From: Unknown Subject: Re: Modems and the NeXT [using a mac cable to connect a modem to your cube] While the mac cable will work for the most part, it can cause some problems. These problems are only apperant when you try to have your modem auto-answer and dial out. In your release notes, you can find the correct wiring for a NeXT to modem cable. Looking up in my Microphone II manual, I find they are not the same. It is understandable that people confuse this issue, after all the pins are labelled the same, what people forget is that RS-232 technology allows for 25 pins, not 8. By using 8, you have to hook up some wires from the 8 pins to the wires on the 25 pin side. You then need a driver to make your 8 pin connector act like the 25 pin connector. Apperantly NeXT and Apple do not see eye to eye on this one. Even though I do not have any connection with NeXT or Apple, this information was gotten through Seena Tamadin who works for NeXT in Chicago. Michael Rutman SoftMed >From: epsilon@wet.UUCP (Eric P. Scott)
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