jacquemin-michel@CS.YALE.EDU (Michel Jacquemin) (06/19/89)
I am looking for any information about synchronous 2400bps modems for a PC/XT compatible. I would use it to connect to an IBM mainframe (using the BSC3780 bisynchronous protocol). Has anybody done this? Any information about synchronous modems would be appreciated. Being able to do async 2400bps (V.22 bis) as well would be a plus. Internal preferred. Michel Jacquemin jacquemin@cs.yale.edu ...!uunet!yale!jacquemin Jacquemin-Michel@YaleCS.BITNET "L'ouie de l'oie de Louis a oui ce que toute oie oie", Raymond Devos
psrc@pegasus.ATT.COM (Paul S. R. Chisholm) (06/23/89)
In article <64114@yale-celray.yale.UUCP>, jacquemin-michel@CS.YALE.EDU (Michel Jacquemin) writes: > I am looking for any information about synchronous 2400bps modems > for a PC/XT compatible. I would use it to connect to an IBM > mainframe (using the BSC3780 bisynchronous protocol). I'm not a modem expert, so take this with a grain of salt. First of all, while it's a good idea to say what you're going to do with what you're looking for, I think that any synchronous modem should handle any synchronous protocol (bisync, SNA, X.25, whatever). > Being able to do async 2400bps (V.22 bis) as well would be a plus. I know that 212-compatible modems can handle either async or sync . . . > Internal preferred. . . . but this won't happen. I'm pretty sure that internal modems have the equivalent of both an async adapter and a modem (except for the power supply). I'm almost positive that 1200 bps internal modems specifically say they're async only. (I'm not a V.anything guru, so things could be different here.) As for a recommendation: I'm not that familiar with our modems, and I don't have a product manual here at home, so I recommend you talk with an AT&T account executive. (Hey, he *asked*!) > Michel Jacquemin, jacquemin@cs.yale.edu, ...!uunet!yale!jacquemin, > Jacquemin-Michel@YaleCS.BITNET Paul S. R. Chisholm, AT&T Bell Laboratories att!pegasus!psrc, psrc@pegasus.att.com, AT&T Mail !psrchisholm I'm not speaking for the company, I'm just speaking my mind. > "L'ouie de l'oie de Louis a oui ce que toute oie oie", Raymond Devos (I loved it when they sang this song in ANIMAL HOUSE, didn't you?-)
durham@handel.mpr.ca (Paul Durham) (06/24/89)
In article <595@pegasus.ATT.COM> psrc@pegasus.ATT.COM (Paul S. R. Chisholm) writes: >In article <64114@yale-celray.yale.UUCP>, jacquemin-michel@CS.YALE.EDU (Michel Jacquemin) writes: >> I am looking for any information about synchronous 2400bps modems >> for a PC/XT compatible. I would use it to connect to an IBM >> mainframe (using the BSC3780 bisynchronous protocol). >> Being able to do async 2400bps (V.22 bis) as well would be a plus. >> Internal preferred. >. . . but this won't happen. I'm pretty sure that internal modems have >the equivalent of both an async adapter and a modem (except for the >power supply). The Hayes 2400B internal modem handles both sync and async ( as does the external version ). It handles this by doing an internal sync to async conversion and moving the data through the 8250 UART ( I am not making this up ). You need a special driver called the Hayes Synchronous Driver or some such thing. There are also firms who sell a sync modem on a card with an 8251 USART or whatever the PC uses for BSC communications, in fact I think you can get a complete package with board and 3780 emulator. Try the ads in PC magazine. P. Durham
wek@point.UUCP (Bill Kuykendall) (06/24/89)
For 3780 bisync you probably want a 201C modem. UDS makes a couple of good models that will do the trick.
bcw@rti.UUCP (Bruce Wright) (07/02/89)
In article <1688@eric.mpr.ca>, durham@handel.mpr.ca (Paul Durham) writes: > > The Hayes 2400B internal modem handles both sync and async ( as does > the external version ). It handles this by doing an internal sync to > async conversion and moving the data through the 8250 UART ( I am > not making this up ). You need a special driver called the Hayes > Synchronous Driver or some such thing. Unfortunately the Hayes modems do not support standard synchronous communications protocols - You can't run BISYNC on them, for example, unless the modem on the other end is also a Hayes modem. It can't talk to standard synchronous modems. If you think about this it should be obvious that in the general case there is no way to put a simple sync modem on an async line - even if you have a UART on the modem to read the line, you don't have any way for the computer to transmit a frame or to identify an incoming frame; often this is important (you don't want to see just streams of bytes in many synchronous protocols, you want to see complete frames). The only way to do it would be define a higher-level (or lower-level, depending on your point of view) protocol which you could use to talk to the modem and which would identify the start and end of the frames. The Hayes modems have not done this - the data looks more-or-less like a stream of bytes with no frame markers; also they use the wrong modulation for a standard synchronous modem. Not to say anything particular against the Hayes modems - they are good products - but they really are not meant as general-purpose synchronous modems; the mode is provided so that communication between identical Hayes modems can be sped up using the sync mode. Bruce C. Wright