DTR toggle on x86

Question

I have been working with a few applications that toggle off and on DTR on /dev/ttyb very quickly. (specifically flipit & bottlerocket for X-10 home automation)
I have compiled successfully with linux (RH 7.0 on i386) , Solaris on an SS5 (Solaris 8 -01/01) - after modifying my running
kernel with adb with a patch for the ZS driver, to allow rapid toggle of DTR)
The problem is, the system does not respond to DTR toggle like it should(quickly), but operation of a modem is fine with tip.
I have turned off the getty for /dev/ttyb with admintool.
There is many threads regarding the ZS & SE drivers with this type of behaviour, but there is no mention of contemporary Solaris X86 exhibiting the same problem.
I have a compiled this code on the sparcstation/x86 with different results.
#include <fcntl.h>
#include <termio.h>
#include <sys/time.h>
#define L 13
#define H 14
/* Global variable (just for this test) */
int port;
void outport(unsigned char x)
int bitset;
switch (x)
case L:
bitset = TIOCM_DTR;
ioctl(port, TIOCMBIS, &bitset);
break;
case H:
bitset = TIOCM_DTR;
ioctl(port, TIOCMBIC, &bitset);
break;
default :
printf("Invalid Status ...\n");
int main(int argc, char **argv)
struct timeval time;
int i;
if ((port = open("/dev/ttyb", O_RDWR | O_NDELAY | O_NOCTTY)) == -1)
printf("Unable to open /dev/ttyb/n");
exit(1);
/* NOTE: output to ttyb is inverted (H->L, L->H) */
for (i=0; i<1000; i++)
outport(H); /* init */
gettimeofday(&time, NULL);
printf("H: %ld.%ld\n", time.tv_sec,time.tv_usec);
outport(L);
gettimeofday(&time, NULL); printf("L:%ld.%ld\n",time.tv_sec,time.tv_usec);
/* close(port); */
The sparcstation(with DTR patch) rapidly toggles DTR, while the X86 toggles seldom.
Help!
/Mark

Answer 1

In Preferences->Appearance, see what the hot area display threshold is set to. It should be 97 or higher.