NH> can anybody tell me how to read a sector from cd rom ?

Rather than debug your code,  I'll give you some of mine that has worked for me:

 #include 
 #include 
 #include 
 #define INCL_DOS
 #define INCL_DOSDEVIOCTL
 #define INCL_NOPMAPI
 #include 
 //#include "y:/cdioctl.h"

 #pragma pack(1)
 /*------------------------------------------------*
  * Cat 0x80, Func 0x72: Read Long                 *
  *------------------------------------------------*/
 struct ReadLong {
         ULONG       ID_code;
         UCHAR       address_mode;
         USHORT      transfer_count;
         ULONG       start_sector;
         UCHAR       reserved;
         UCHAR       interleave_size;
         UCHAR       interleave_skip_factor;
 };
 #pragma pack()

 HFILE opendrive(char *drstr, char mode)
 {
     HFILE fh;
     ULONG usAction, stat;
     ULONG open_mode;
     ULONG bCmd;

     open_mode = OPEN_FLAGS_DASD | OPEN_SHARE_DENYREADWRITE
                 | OPEN_FLAGS_WRITE_THROUGH | OPEN_FLAGS_FAIL_ON_ERROR
                 | OPEN_FLAGS_NOINHERIT;

     if(mode == 'w')
         open_mode |= OPEN_ACCESS_READWRITE;

     stat = DosOpen(drstr,      /* filename to open              */
         &fh,                   /* address of file handle        */
         &usAction,             /* address to store action taken */
         0L,                    /* size of new file              */
         0,                     /* file's attribute              */
         FILE_OPEN,             /* action to take if file exists */
         open_mode,             /* file's open mode              */
         0L);                   /* Reserved                      */
     if(stat){
         switch(stat){
             case 15:
                 printf("Drive %s is invalid.\n", drstr);
                 break;
             case 21:
                 printf("Drive %s is not ready.\n", drstr);
                 break;
             case 32:
                 printf("Drive %s is currently locked by another
process.\n", drstr);
                 break;
             case 65:
                 printf("Drive %s is a network drive.\n", drstr);
                 break;
             default:
                 printf("error %d opening drive %s\n", stat, drstr);
         }
         exit(3);
     }
 #if 0
     bCmd = 0;
     stat = DosDevIOCtl(0L, &bCmd, DSK_LOCKDRIVE, IOCTL_DISK, fh);
     if(stat){
         printf("Error %d locking drive\n", stat);
         exit(3);
     }
 #endif
     return(fh);
 }

 void dump(char *buf, int b)
 {
     int i;
 #if 1
     for(i=0; i128 || isprint(buf[i]))
             putchar(buf[i]);
         else
             putchar('.');
     }
 #endif
 }

 int main(void)
 {
     HFILE hf;
     static char buf[6000];
     APIRET rc;
     struct ReadLong rl;
     ULONG ulPinout, ulDinout;

     memset(buf, 1, sizeof(buf));
     hf = opendrive("J:", 'r');

     ulPinout = sizeof(rl);
     ulDinout = sizeof(buf);

     rl.ID_code                  = 0x31304443L;    // "CD01"
     rl.address_mode             = 0;
     rl.transfer_count           = 2;
     rl.start_sector             = 1000;
     rl.reserved                 = 0;
     rl.interleave_size          = 0;
     rl.interleave_skip_factor   = 0;

     rc = DosDevIOCtl(hf,
                     IOCTL_CDROMDISK,
                     CDROMDISK_READLONG,
                     &rl, sizeof(rl), &ulPinout,     /* parms */
                     buf, sizeof(buf), &ulDinout);                /* data */

     if(rc)
         printf("sys%04u: IOCD_READ_LONG error\n", rc);
     else
         dump(buf, 3000);
     exit(0);
 }


--- Maximus/2 3.00