From: garycrowley AT musician DOT org
Newsgroups: comp.os.msdos.djgpp
Subject: BIOS serial port int 14h
Date: Mon, 07 Aug 2000 14:17:34 +0100
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

I'm having trouble with the BIOS serial port routines provided by int
14h. I'm trying to write a really elementary BBS type program which
takes characters from the keyboard, and throws them at a serial port;
and vice versa, takes input from the serial port and displays them.

In an MSDOS box under Win2000, a version of this program just about
works, although it echoed characters seem to lag behind transmitted
characters. In MSDOS under Win98, it gives the following results;

C:\a-mterm>mterm
6030
41,54,44,54,34,30,37,32,34,35,31,32,39,39,d,(8000, )(8000, )(8000,
)>>13<[d]>>13
<[d]>>13<[d](8000, )(8000, )>>13<[d]>>13<[d]>>13<[d]>>13<[d](8000, )^C

It just prints out a load of 0x8000 which means it can't read
anything. 'sport' is set appropriately for the COM port, COM3 for
Win2k and COM2 for Win98 (for some reason the COM ports are different
under the different OS's with identical hardware).

I'm really asking for some help here. I've seen other terminal
emulators which directly muck around with OUTP and INP but I'd prefer
to use int 14h. What is going wrong? My experience of programming this
sort of thing is very small. Is there a fault with the way I'm doing
this, or is there a problem in my Win98 configuration? A simple
INP/OUTP BBS program works in win98.

Alternatively, can someone point me towards a small BBS program based
on int 14h which I can adapt to my purposes?

Help, please!



#include <stdio.h>
#include <bios.h>
#include <conio.h>

// int _bios_serialcom(unsigned service, unsigned port, unsigned
data);
void sendkeys(unsigned sport, char *keys);

main()
{
unsigned int i, k=0, sport=2;	// com3 == '2'

printf("%x\n",_bios_serialcom(0,sport,0xe2));

sendkeys(sport,"ATDT2370400\r");

while(1)
{
if(k>0) { printf("[%x]",_bios_serialcom(1,sport,k)); k=0; }
if(kbhit()) { printf(">"); k=getch(); printf(">%d<",k); continue; }

// i=_bios_serialcom(3,sport,'\0'); if(i!=0x6030) printf(";%x;",i);
i=_bios_serialcom(2,sport,'\0'); { printf("(%x,%c)",i,i&0xff); }
}

printf("\nend\n");
}


void sendkeys(unsigned sport, char *keys)
{
	char *p=keys;

	while(*p) printf("%x,",_bios_serialcom(1,sport,*p++));
}