pmh@burl.UUCP (Peter M. Hermsen) (07/11/84)
-- Ok all you 1200 baud fanatics out there in net land. Has anyone thought of looking at EXAR for their 1200 baud chip set? How about the set of : 1. XR-14412 FSK Modem 300 Baud 2. XR-2120 Filter-Switched Capacitor 3. XR-2123 PSK modem 1200 Baud The chips listed above are available for about $65.00 total in single quantities from EXAR's distrubutors. There was a good article in EDN magazine concerning these chips and the modem they constitute when assembled as a unit with a few vanilla flavored CMOS devices and 2 LSTTL's. By the way, the issue that had the article was EDN May 17, 1984. The article "Low-cost modem circuit meets Bell Standard 212A" was submitted by Jim Lange at EXAR. (Let's give credit where credit is due.) I called EXAR and they sent me a complete schematic, board layout and source listing (8748 controller optional). The address is: EXAR Integrated Systems, Inc. 750 Palomar Avenue Sunnyvale, CA 94086 (408) 732-7970 Give them a call or drop them a line. The info they provide is very useful. Disclaimer: I have no affiliation with EXAR. I am offering this article as a public service :-). -- -- From the non-linear mind of a non-anonymous hacker!! Pete Hermsen ihnp4! \ PO Box 2304 akgua! \burl!pmh Burlington, NC 27216 cornell! / (919) 228-4215 (w) ulysses!/ "Not all roads lead to Hollywood..."
cem@intelca.UUCP (Chuck McManis) (07/16/84)
Yet another VLSI solution to the modem game is T.I.s new chip set
numbered the TMS99532 FSK Chip, TMS99531 Dialer Chip, TMS99542 PSK Chip.
In the June 14th issue of Electronics Design, page 261 there is an
article on implmenting a "triple modem" (ie Bell 103, 212a, and Racal Vadic
V3400) with these three chips and a micro controller (single chip MPU)
With the microcontroller and the DAA (phone hookup) you can build your
own smart modem. Since the uC can be had for <$100 the whole modem should
be less than $200. Cheaper still if you use something like an 8048.
It is quite a reasonable article and goes on to describe the various formats
around. Highly reccomended.
--Chuck
--
-- Chuck - - - D I S C L A I M E R - - -
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