The following tutorial explains using the FDISK DOS application to set up a partition on a new hard drive or to delete an existing hard drive before clean-installing an operating system (OS). This is done using the Windows 98 SE boot disk.
Windows 98 SE boot disk
Remember that deleting a partition is equal to formatting your hard drive.
Back up what you want to CD or DVD.
Step 1 – Deleting Existing Partitions (Use these instructions if you are not using a new hard drive and want to delete your old one.)
a. We will need to change the BIOS/CMOS settings so your PC will boot to floppy first.
b. Insert the Windows 98 boot disk, and reboot your PC.
c. It will bring up a Windows 98 Startup Menu screen. Choose the first option, Start Computer with CD-ROM support. The boot disk will load and eventually return to a A:\
d. At the A:\, type: FDISK
e. This will now load the FDISK utility. The first screen might contain the question, “Do you wish to enable large disk support?” Choose Y for “Yes.” Also, if your C: was formatted as a NTFS drive rather than FAT32, it might also ask you if you want to treat non-FAT drives as unknown. Again, choose Y for “Yes.”
Now, you should be at the FDISK menu.
f. First, we will  Display Partition Information to see what we have set up and what we need to delete.
g. Once we see what we have set up, Esc back to the main FDISK menu. Then go to  Delete partition or Logical DOS Drive.
Now, it will bring up four options:
1. Delete Primary DOS Partition
2. Delete Extended DOS Partition
3. Delete Logical DOS Drive(s) in the Extended DOS Partition
4. Delete Non-DOS Partition
When you delete partitions, here are some basic guidelines:
Delete partitions first to last as follows:
-Non-DOS > Logical DOS Drive(s) > Extended DOS Partition(s) > Primary DOS Partition
-If you have any NTFS drives, if possible, try to delete them in Windows before booting to floppy. This makes the process easier, especially if the parition is created in an Extended DOS Partition. When trying to delete them from FDISK, you might receive the message, “Cannot Delete Extended DOS partition while logcal drives exist.” However, when you try to delete the logical drive, you receive the message that none exist. If this is the case, I usually quick-start install XP. Once the XP setup gets to the disk part, I delete the NTFS partition from there, and then start my whole installation from scratch again. (Delete all partitions, and create new ones.)
Once you have deleted all of the partitions, go back to the main FDISK menu and to the next step.
Step 2 – Creating Partitions with FDISK (As an example, I will use a 60GB hard drive)
a. First, decide if you want to use the whole hard drive for one partition or if you want to set up multiple partitions (i.e., c: drive and d: drive).
b. e should still be on the FDISK menu (below).
Choose one of the following:
1. Create DOS partition or Logical DOS Drive
2. Set active partition
3. Delete partition or Logical DOS Drive
4. Display partition information
Enter choice: 
Press Esc to exit FDISK
c. Go to  Create DOS partition or Logical DOS Drive
d. Then go to  Create Primary DOS Partition
If you have a Primary DOS partition, you will receive a message stating, “Primary DOS Partition already exists.” You will need to delete this. (put in italics, smaller)
e. You will now receive a message, verifying drive integrity. Once this is done, you will see the question:
“Do You wish to use maximum available size for a primary DOS partition and make the partition active (Y/N)?”
Choose N if you want to set up multiple partitions (picture below) or Y to create just one partition and make it the full size of the hard drive:
Create Primary DOS partition
Current fixed disk drive : 1
Verifying drive integrity, 100% complete.
Current fixed disk drive: 1
Do you wish to use the maximum available size for a primary DOS partition
and make the partition active (Y/N) ………………..? [N]
f.(optional) If you are setting up more than one partition, it will now ask what size partition you want to create in either bytes or in a percentage (xx%). Also, you might notice that the space free/available might not be equivalent to the size of your hard drive (if it is bigger than 20 GB). This is because FDISK is limited to seeing up to 20 GB (if my memory is correct). I recommend creating partitions based on percentage. In my example, I have 60GB hard drive, so I am going to create this partition to be about 15GB. To do this, I would find out what percent of 60 GB is 15 GB.
After the math, 25% will equal approximately 15 GB.
Enter the percentage as follows: xx%. (Be sure to put in the percent sign, or it will take the value as size in bytes.) Then hit Enter, and your partitions will be created.
g. Once this finishes, it will bring you to this screen. Just ESC to the FDISK menu. At the bottom of the FDISK menu, you should see a message:
WARNING! No partitions are set active – disk 1 is not startable unless a partition is set active.
h. Go to  Set active partition and enter the number of the partition set as active. It will let you know that Partition 1 has been made active.
i. Now, ESC all the way back to to the DOS Prompt (a:\), and reboot your computer. Be sure to leave the boot disk in since we will need to format the drive we just created.
Step 3 – Formatting the Drive / Pre-installation
a. Again, choose to start with cd-rom support and let the boot disk load to the a:\ DOS prompt.
b. Type format c: and follow the prompts.
c. This might take a few minutes to complete. Let it finish.
d. After you have the c: drive formatted, we are ready to install an OS!