Using a U.S. Robotics Fax modem with Slackware 10.0 3922

In a message on Fri, 17 Jun 2005 13:31:56 -0400, wrote :

Only if you are using *hardware* (BIOS supported) serial ports. I think what is happening here is that Linux 'reserves' COM1 (ttyS0) ... COM4 (ttyS3) to the standard four serial ports (at the 'standard' addresses). PCI based real modems and other sorts of serial ports get device names allocated differently. An ISA BOCA 4 or 8 port board will be up at ttyS16 and up for example. My guess is that the serial port on the USR 5610B PCI modem is also getting a 'dynamically' allocated ttyS number. Or else the probe code in serial.c is using some mapping of port names (minor numbers) to specific sorts of hardware. Somewhere in the depths of serial.c (or someplace like that) there is a mapping of sorts of serial port hardware and minor numbers (device names). Bare MS-DOS cannot access anything beyond COM1,2,3,4 without special hackery. Linux is not limited (can handle lots of serial ports). Mess-Windows NT-ish is not limited either, but is probably playing games to fake the port name to be COM3 for mess-dos compatibility reasons (in case someone wants to use a MS-DOS-ish serial port program, like an old, dumb mess-dos based terminal emulator). Actually, MS-Windows has to use COM1...COM4 to be compatible with ANY software expecting to talk to a 'COM' port. Although there is no technical reason for any NT-flavor of MS-Windows (NT 4, NT 5.0-W2K, NT 5.1-WinXP) for referencing something like COM5 (aka ttyS4), 'COM5' makes no sense in terms of the low-level BIOS, since the BIOS cannot handle something like COM5. What pbuttes for 'minor numbers' under MS-DOS only allows for 4 ports.

Hardware (RS232 serial port) modems are all the same (buttuming Hayes command set and all current model consumer-grade RS232 serial port modems are Hayes command set). The low-level driver ({8,16}550B-registers) is serial.c and the upper level (Hayes command set) is in in wvdial-chat-whatever. The only variations between these modems are in the 'extended' commands relating to higher speeds and various settings and reports, none of which are actually needed for base dialing. All of these modems understand the commands like ATZ and ATD. Everything else is implemented with customizable 'init' strings and-or with 'dial prefixes' and such -- all a function of diddling theetc-wvdial.conf file.

The 'driver' software that comes with these modems for Windblows is mostly just init and dial prefix strings and-or eye-candy nonsense (containing the model number and not much else) layered on top of generic driver software.