🚀 go-pugleaf

I'm posting here because I think my problems have to do with 
dos, not c.  Correct me if I'm wrong.

The program below does nothing but store lines from a file in
malloced memory and then attempt to free that memory.  I was
getting "exception 13" from QEMM, the manual said that often
meant segment wraparound, which I don't really understand,
but I guessed that using far pointers would make it less likely,
and it seems to've worked.  But now the compiler (Borland C++ 2.0)
complains about suspicious pointer conversions.

Can someone point me to an introductory article on pc segments?
Is there a way to avoid dealing with this when using dos?  Or do
I just have a bug in my program?

I also don't understand the numbers I get from coreleft.  They
show memory sucked up after the mallocing, as I'd expect, but 
none freed at all until the very last free, when it is all freed
at once.  I thought this was perhaps because malloc works with
chunks of memory, but even when I do huge files I get the same 
pattern.

------
#include <stdio.h>
#include "lines.h"
#include <alloc.h>

main(int argc, char ** argv)
{
    FILE *infile ;
    struct line linedesc ;
    struct line far *linedescp, far *nextlinep ;
    char buffer[MAXLINE+1] ;

    infile = fopen(argv[1], "rt") ;
    if(infile == NULL)
    {
        printf("Can't open %s for reading", argv[1]) ;
        exit(-1) ;
    }
    printf("before: %u\n", coreleft()) ;
    linedescp = &linedesc ;
    while(fgets(buffer, MAXLINE, infile))
    {
        linedescp->text = (char *) malloc(strlen(buffer)+1) ;
        strcpy(linedescp->text, buffer) ;
        linedescp->next = (struct line far *) malloc(sizeof(struct line)) ;
        linedescp = linedescp->next ;
    }
    linedescp->text = NULL ;
    linedescp->next = NULL ;
    printf("after: %u\n", coreleft()) ;

    /* now free it all */

    linedescp = &linedesc ;
    while(linedescp->text != NULL)
    {
        free(linedescp->text) ;
        nextlinep = linedescp->next ;
        free(linedescp) ;
        linedescp = nextlinep ;
     }
     printf("Before last free: %u\n", coreleft()) ;
     /* freed all but last element.  free the linedesc, but nothing was
        malloced for text, so don't free -> text */
     free(linedescp) ;
     printf("After last free: %u\n", coreleft()) ;
     return ;
}
---lines.h---
struct line
{
    char *text ;
    struct line far *next ;
    struct line far *prev ;
} ;

#define MAXLINE 200