dieter@beta.DEC (07/30/85)
2400 bps modems - reply >I was wondering about the compatibility of 2400 baud modems. > >ie: > >1) What different types of protocols are there, or aren't there? >2) Specifically, we have a bunch of ATTIS and Concords, which > are compatible, but how compatable are they with DECS new > DF-224s? >3) Which ones perform well, and which ones don't. >4) Is there a prevailing standard, or does it look like there > is going to be one. 1. Most modem vendors offer their own autodial protocol. Lately many have been implementing the Hayes protocol also, in one of two ways. One way is to offer two models, one with Hayes and one with their own. The other is to put the choice in the modem(Penril does this). At Interface many vendors criticized the Hayes protocol but sheepishly admitted that the marketplace demanded it. The DF224 does not support the Hayes protocol, it is unique like the ATTIS and some others. 2. The DF224 was tested with the CDS, Hayes, and Vadic it should be compatible with any other V.22bis modem - especially if it uses the Rockwell chip set (most of the market). 3. Of course the DF224 (Scholar) performs the best! What else could I say... Actually most of the V.22bis modems will be very similar, and we would expect all of the modems made with the Rockwell chips to work the same. 4. I presume the standard referred to is the Autodial method. The perception is that the Hayes autocall method is the most widespread...don't know if its true but it perceived to be so. Mostly due to Smartcomm software making life easy for PC users. The DF224 autocall method is very easy to use and the modem has an extensive menu, 15 stored numbers, redial, nametag calling, etc. I notice that the Hayes 1200 and 2400 versions are different, I wonder how much pain that has caused users wanting to upgrade. The initial question was about compatibility, I think you will find most of the recent V.22bis modems will be very similar. Most will also implement the fall back mode to be Bell 212A compatible rather than V.22. Those that adaptively equalize to the line in 1200 mode will work where a 212 will not. Ralph Dieter DEC Merrimack, NH