How to correctly read hard drive partitions?

Question

I need to read all 4 hard drive partitions and display them on the screen.

Everything is fine with the output, but there is a problem with reading the partitions themselves. I don’t understand what to change - the head, cylinder or sector. I tried changing all these values ​​and something is always read, which is why I don't really understand whether I read everything correctly.

The program is written in C using Borland C++ (TurboC). I work in Windows 98.

What information needs to be displayed about the section:

Offset Length Contents
+0      1       Boot Flag- boot flag: 0=not active, 80h=active.
+1      1       Begin Hd - start of section: head (side) number.
+2      2       Begin Sec/Cyl – start of section: sector/cylinder. 
+4      1       System Code – file system code.
+5      1       Ending Hd – end of section: head number. 
+6      2       Ending Sec/Cyl – end of section: sector/cylinder of the last sector. 
+8      4       Starting Sector – logical number of the starting sector of the partition (address in
                LBA system). 
+0Ch    4       Num Sectors – partition size (number of sectors)

Program code:

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

//#define NUM_PARTITIONS 4

unsigned char buf[512];

int read_mbr() {
    union REGS in, out;
    struct SREGS sr;
    int i = 0;
    int j = 0;

    for (; i < 64; i += 16, j++) {
        sr.es = FP_SEG(buf + i);
        in.x.bx = FP_OFF(buf + i);

        in.h.ah = 0x02;
        in.h.al = 1;
        in.h.dl = 0x80 + j;
        in.h.dh = 0;
        in.h.cl = 1;
        in.h.ch = 0;

        int86x(0x13, &in, &out, &sr);

        if (out.x.cflag || out.h.ah)
            return 1;

        printf("%d", j);
    }

    return 0;
}

int get_count_partitions() {                                         
    int numPartitions = 0;
    int i = 0x1BE;

    for (; i <= 0x1EE; i += 16) {
        numPartitions++;
    }

    return numPartitions;
}

void extract_partition_info(int partition_number) {
    unsigned char beginHd = buf[1];
    unsigned short beginSecCyl = *((unsigned short*)(buf + 2));

    // Print the extracted partition information
    printf("Partition %d:\n", partition_number);
    printf("Begin Hd: %u\n", beginHd);
    printf("Begin Sec/Cyl: %u\n", beginSecCyl);
}

void print_partition_info(unsigned char* partition_entry, int partition_number) {
    unsigned char bootFlag = partition_entry[0];
    unsigned char beginHd = partition_entry[1];
    unsigned short beginSecCyl = *((unsigned short*)(partition_entry + 2));
    unsigned char systemCode = partition_entry[4];
    unsigned char endingHd = partition_entry[5];
    unsigned short endingSecCyl = *((unsigned short*)(partition_entry + 6));
    unsigned int startingSector = *((unsigned int*)(partition_entry + 8));
    unsigned int numSectors = *((unsigned int*)(partition_entry + 0x0C));

    printf("Partition %d:\n", partition_number);
    printf("Boot Flag: 0x%02X\n", bootFlag);
    printf("Begin Hd: %u\n", beginHd);
    printf("Begin Sec/Cyl: %u\n", beginSecCyl);
    printf("System Code: 0x%02X\n", systemCode);
    printf("Ending Hd: %u\n", endingHd);
    printf("Ending Sec/Cyl: %u\n", endingSecCyl);
    printf("Starting Sector (LBA): %u\n", startingSector);
    printf("Number of Sectors: %u\n", numSectors);
    printf("Root Boot Sector Address (LBA): %u\n", startingSector);
}

int main() {

    int i = 0;
    int j = 0;

    clrscr();

    if (read_mbr())
        printf("Error reading sector\n");
    else
        printf("Sector read successfully\n");

    printf("Number of sections: %d\n", get_count_partitions());
    extract_partition_info(1);

    getch();
    clrscr();

    for(;j < 512; j++)
        printf("%d",(int)buf[j]);
    getch();

    for (; i < 64; i += 16){
        clrscr();
        print_partition_info(&buf[i], (i/16 + 1));
        getch();
    } 

    return 0;
}