Description

This article is from the 3b1 computers FAQ, by John B. Bunch with numerous contributions by others.

4.10. Why doesn't the On-Board Modem (OBM) work with some other modems?

One problem is that the OBM seems to create answerback tones which identifies itself (for some reason) as an MNP reliable modem (!). This confuses some MNP modems and the Telebit Trailblazer (only if set in MNP reliable mode). These cannot be altered in the OBM, but often a system which cannot call the UNIX PC OBM can be called by the UNIX PC OBM.

Another problem is that the OBM has trouble establishing a UUCP connection when calling Telebits configured in locked-speed mode. Chris Lewis (clewis@ferret.ocunix.on.ca) has written a program called phfix which can be invoked from /etc/rc to correct this particular problem using the (undocumented?) PIOCOVSPD setting on the OBM. The result is that the OBM can successfully connect with locked-speed Telebits, and they can connect back. The program is not on OSU or in any comp.sources.3b1 archives, so it is presented here:

/*	Sample program for bashing the OBM into tone dial and
setting PIOCOVSPD to permit talking to certain modems
(particularly telebits).
The documentation mentions 2.3% speed change for PIOCOVSPD.
That's all I know.
  
You are free to do whatever you wish with this code, but
please leave this comment in.
  
Chris Lewis, clewis@ecicrl.uucp, Jan 2 1991.
 */
#include <stdio.h>
#include <fcntl.h>
#include <sys/phone.h>
  
main(argc, argv)
int argc; char **argv; {
    int f;
    struct updata upd;
    f = open("/dev/ph1", O_RDWR | O_NDELAY, 0);
    if (f < 0) {
perror("/dev/ph1");
exit(1);
    }
    ioctl(f, PIOCGETP, &upd);	/* retrieve Phone parameters */
  
#ifdef	NEVER
    /* if you want to play with these go ahead - for some reason my
       3b1 always comes up in PULSE */
    upd.c_lineparam &= ~PULSE;	/* reverse the sense to set to pulse dial */
    upd.c_lineparam |= DTMF;	/* reverse the sense to set to pulse dial */
  
    upd.c_feedback |= SPEAKERON;
    upd.c_feedback |= LOUDSPK;
    ioctl(f, PIOCDISC, &upd);	/* apply PIOCOVSPD for talking to some modems*/
#endif
  
    ioctl(f, PIOCOVSPD, &upd);	/* apply PIOCOVSPD for talking to some modems,
			   eg: Telebits */
    ioctl(f, PIOCSETP, &upd);	/* set phone parameters */
}

 

Continue to:

• prev: 4.9. Is HoneyDanBer UUCP available to replace the stock uucp software?
• Index
• next: 4.11. How do I get my on-board modem to be a dial-out-only modem?

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