pn@ucb-vax.arpa (02/16/83)
I have recently purchased a Hayes Smartmodem 1200 ($599), and after using it for a couple of days, have the following comments concerning it: (these comments have a Unix/UUCP bias, so be forewarned) 1) THE MUCH MALIGNED "ESCAPE CODE" I have heard complaints about the modem going into command mode after receiving a "+++" sequence. It is possible to change the escape character to any ASCII character, or to completely disable this feature. I quote the manual "(An ASCII value) greater than 127 will completely disable escape code detection and prevent you from issuing a hang up command, since you cannot return to local command state. To disconnect when the escape code is disabled, the distant modem must hang up or you must turn off the DTR lead on the RS-232C connector." For autodialer use (ala Ventel 212+), this is perfect. DEC DHDM serial interfaces provide the ability to manipulate DTR, and the Unix tty driver knows about it. There is *no* problem sending binary data down a properly configured Hayes Smartmodem. Just disable escape codes, do an IOCTL(TIOCHPCL), transmit your data, and then when done, close the port, which will drop DTR, causing the Hayes to hang up. For normal use from a terminal, note that the escape sequence must be surrounded by an idle time of 1 second on either side before it will be recognized. 1 second is actually a long time, and it is unlikely you will accidentally go into command mode. 2) DIALING The Hayes is the ONLY autodialer I have found which will let you start out pulse dialing (my company actually has a pulse only CBX) and then switch to tone dialing in the MIDDLE of the number. This also means people who only have pulse dialing enabled on their private lines can use the Hayes with MCI style services. Note a lot of modems can only pulse dial. (the Novation can't dial at all, despite what their ads may mislead you to believe. you have to shake the OFF-HOOK pin they provide to pulse dial, but you need a computer with a parallel port you can rewire to do that.) 3) AUTO-BAUDING This may not be the right term, but what I mean is the ability of the auto-dialer to figure out what baud rate your terminal is at. The Ventel requires 2 CRs with a fairly critical time interval in between (if you're using sleep(1), at least) before you can talk to it. In addition, if you want to change baud rates, you have to drop DTR and CR CR again. The Hayes takes a "A" and figures out if you're 300 or 1200 baud. Much simpler. Also, you can give a command at 1200 baud and then the next one (if the first number was busy, for example) at 300 baud without any explicit re-auto-bauding. (each command starts with an "A") 4) SPEAKER The Hayes has a built-in speaker, which can be disabled by software, to allow you to monitor the progress of the call. This really is wonderful if you've never tried it. Well, I could go on and on about how I love this modem, but my primary intent in writing this article was to give people a more accurate description of the Hayes' features. THIS IS A WELL THOUGHT OUT AUTODIALER.... It is also a nice modem and comes with a nice manual (almost as good as HP calculators). phil ngai ucbvax!amd70!pn