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Guide to FDISK


- Re-format, partition, and rebuild your drive with FDISK  

A blast from the past! I wrote this floppy disc tute about ten years ago as a memory aid for myself when learning how to use FDISK, since there are 25 steps involved. Amazingly, it is still valid today - engineers and advanced users still use this method either by preference or when repairing disk errors. You can burn the files to CD but a machine with a proper floppy disk A:\ drive is always a superior choice, just as a laptop with a serial port is always the engineer's first choice.


FDISK - the step-by-step guide

This is a step by step guide to FDISK - a guide to the complete process - all the steps needed to partition, format, and load the Operating System (Windows etc.) onto a hard drive, using the FDISK utility on a 3.5 inch floppy boot disc. The other uses of FDISK aren't covered because we want to concentrate on the most important area.

You can also burn the files onto a CD and use that instead, if you don't have a floppy drive. If you do this, instead of drive A:, you'll most likely be using drive D: in the following instructions.
If you're new to this – or even if you aren't, but would appreciate an aide-memoire – this will be handy, as there are actually 25 steps to reformatting. Whenever someone's advice is sought on this, they always give you about five or six steps to do; which leaves you scratching your head over the missing twenty. To the best of my knowledge, this is the only full guide to reformatting with FDISK – I've never seen this listed anywhere else. There must be many people who have had to give up half-way, often due to problems with the DOS commands, which are totally foreign to Windows users now.

Is FDISK for beginners?

This is an engineers' and advanced users' style of reformat; users will normally employ a bootable CD or a third-party app for this. However, when the machine has difficulties, or crashes irretrievably, this is the method engineers employ. In fact this will always be useful information for engineers and advanced users, because the days when all machines can boot from all Windows CDs are not only still a long way off, but in fact will never come. Even if all current Windows CDs were to be bootable (i.e. you could format and install a clean new OS on the drive from the CD), this does not apply to any Windows OS in the past. You cannot boot from all W98, W98SE, WME, W2K, and XP CDs (see later). We will be using these for a long time to come, to run valuable software that will not run on anything else. In fact you could of course make yourself a bootable version of a Windows non-bootable CD, if you had to; but with a knowledge of FDISK, it's not necessary.

FDISK is also useful when the CD drive is faulty, or locked out by a faulty BIOS; and when disk operations have to be done in DOS, such as when there are errors or if a particularly tough virus has to be evicted.

I believe FDISK can be used by anyone not afraid to tackle technical issues, even if inexperienced. This is because if a printed crib sheet is used (like this one), it's hard to go too far wrong. And in any case we're talking about a disk that is not in use and cannot be used until rebuilt. We all started somewhere and at some stage you will have to jump in with both feet - this is as good a place as any. Any user with technical ambitions will have to learn how to use the command line and DOS.

How to get FDISK

There are several options. If you have a Windows 98 disc then you will find FDISK on the boot floppy that you create. This applies to most Windows boot floppies. If you need it on CD then again, it will be in the recovery media that you create from within Windows.

Or, you can download it here:

You can build a fine boot CD with extra tools on it, using your Windows CD and the UBCD4Win application. This is BartPE plus additional options:

You can also download FDISK alternatives from several sources - just search for 'fdisk download'.

How to reformat

Here, we describe the process of reformatting a previously-used drive. Formatting a new HD is virtually the same, except:
  • You don't first have to delete any partitions.

  • You may find that your new HD is not recognised by the PC, in which case you will need a hard disk installation app.

  • If you buy a Retail Box hard drive, as against a cheaper OEM Pack, you will often get the manufacturer's HD installation floppy, which contains their special HD installer. These are often based around DiskManager DiskGo. Alternatively this can be downloaded from the HD makers' website. FDISK is normally also included, in an easier to use package.


A partition is a section on the hard disk which is dedicated to one particular operating system or group of data. It needs to be formatted before use or re-use. This process removes any previous data and divides the space up into small parts of a uniform and recognisable size. Note that ALL PREVIOUS DATA WILL BE LOST and the disk will be wiped*. This is a very good reason why re-formatting is carried out occasionally as a maintenance exercise: it's an excellent way of cleaning all sorts of unwanted accumulated dross off the PC.
* A word of caution: when we say 'wiped' we mean as regards all user data. There are two caveats to bear in mind:

1. A reformat actually only removes the file indexing system – the files are all still there. Less than 1% of data is actually removed, and therefore the original files are still recoverable by a data retrieval specialist. If you need to actually wipe the disk clean of all data for security, you must use a specialist application for this. They normally run from a boot floppy, like DBAN / Boot&Nuke for instance, and overwrite the disk many times until every individual section has been written-to several times. One pass is thought to be insufficient, it takes at least 5 passes for complete erasure. This takes longer than most people are prepared to wait.

2. The boot sector is not wiped, and therefore some types of virus may still remain. In addition, it is now also thought possible by some that since the actual data is not removed by a reformat, there may be a chance that some viruses can survive and re-generate. As viruses and their coders become more and more sophisticated, these sorts of problems become more likely. For instance, some experts say that 20% of PCs are Botnet slaves; but it is highly doubtful that one in five PC owners would be likely to agree. Who knows the real situation? 

3. ....but don't worry about any of this - it might only affect one machine in 100k.

Make a new boot disc 

Prior to re-formatting, make a boot disc from your existing operating system. Go to Start - Help to see how to do this. You will need one floppy for most Windows OSs, but four for W2K. As an aside, it's not a bad idea to make another boot disc now and then and keep it. All boot discs are definitely not created equal, and one will prove to be able to fix a problem, on yours or somebody else's machine, whereas others will fail. This applies especially to W2K boot discs, which often turn out to have been corrupted in the making, and have to be re-done several times to get a functional four-disc set.
TEST A W2K BOOT DISC SET IMMEDIATELY you have made it, by trying to boot up with it (no harm will be done to your current installation). Also, boot discs can be corrupted by placing them next to a speaker AND ESPECIALLY a CRT monitor, since they are recorded magnetically. Monitors sometimes use a degaussing burst on boot-up, and this will be just fine for your floppies! 

FDISK Notes 

1. FDISK stands for Fixed Disk, i.e. a utility for a non-removable drive (not format disk).
2. Only your first CD drive may work during this process.
3. W2K will not install from a W98 boot disc. The first part of the process will, and it's quicker, as you're only using one disc instead of four. From there on, you need to insert the W2K set of four boot discs. Solution: if you only have a W2K CD, and not a set of boot discs, then install W98 and upgrade it to W2K with the W2K CD. Then make your boot discs – checking them immediately by booting with them. Often one of the series is no good, and has to be re-done.
In the following instructions:

= hard drive or hard disk
= hit the Enter/carriage return key
Type <xyz>
= type in the three letters xyz. All typed commands can be in upper or lower case, it makes no difference
Boot, or boot up
= switch the PC on
= switch the PC off, then on again – in practice this means hit the reset button, usually below the main power On button, on the front of the ATX case. In FDISK, hitting Cntrl+Alt+Del also works.
= the Escape key
= operating system, i.e. Windows 98, Linux etc
Disc / Disk                   
= media type: removable media such as floppies and CDs are spelt disc, and 'fixed' drives are spelt disk, by convention



Finally, a word to the wise. Print this out now, since you won't be able to access it when you are fdisk-ing. Dohhh! 

How to get to FDISK if the PC boots straight to the hard disk, C-drive, OS

The boot drive sequence is set in the BIOS, aka the CMOS settings. This means, when you boot the PC or laptop, it looks for a drive to boot from, in sequence. You can reset this sequence. Most computers are set by default to boot straight from the C-drive, ie the main hard drive. However, someone who is technically-aware (as against your kids and so on) would be better off resetting this to boot to A - D - C-drive, in that order. In other words - to the Floppy Drive - then the CD drive - then the hard drive. If the computer doesn't find an operating system in any drive it moves on to the next one, though it can stick there if there is any kind of media inserted. An OS (operating system) can be tiny, easily contained on a floppy.

To get into the BIOS, which is the firmware that drives the computer before a software OS kicks in, boot up and hold down the BIOS key. This varies between PCs but is often the Del key, spacebar, or F8. If not - find out which it is for your PC. This, by the way, is not Safe Mode - that is an unrelated option.

Once in BIOS, it's best not to play around if this is unfamiliar territory - you can cripple the computer. Find the drive boot sequence and alter it to 1: A -- 2: D -- 3: C. This assumes that your drives are as identified here, A, D, and C. Save and exit. The PC continues to boot. You can reboot using Cntrl+Alt+Del or the reset button.

Hitting those 3 keys at the same time is a software reboot, hitting the reset button is a hardware reboot. Generally, a software reboot is kinder to the machine but it doesn't make much difference.

These are a special case because they work slightly differently. The power is always on, with a laptop, as the battery is always connected. To hardware-reboot a laptop, hit or hold down the power button. This can take up to 30 seconds to work if an OS is jammed up.

Many seemingly-tricky glitches can be fixed on a laptop by using a 'hard reset', like this: power down (switch off) -- disconnect the mains power supply unit (PSU) -- unclip and remove the battery -- hit the power button 3 times -- reinsert the battery -- reconnect the PSU -- reboot. You'll find this clears all sorts of jam-ups. Hitting the power button during the period with no power connected discharges any stored voltage, power held by capacitative effects, etc. Otherwise you can just leave it disconnected for 20 minutes.

FDISK step-by-step guide

To re-format the hard drive and install a clean OS 

1. If you are installing Windows 98, boot up with a Windows 98 boot disc in (W98 boot floppy in Drive A). From the option list, select (1) Start computer with CD-ROM support, and Enter. Boot file loading and HD checking starts up. If you are installing Windows 2000, you can also boot with a W98 boot disc – for the first bit only – or with the four W2K boot discs.

2. After a while, this process ends and a prompt appears - A:\>, with a blinking cursor, at the beginning of the line. Type <fdisk> and Enter. Try not to insert any additional letters after the 'f' and before the 'd', although working with DOS, our modern version of Greek, may make you want to...

3. At the prompt 'Do you wish to enable large disk support?' select (Y) and Enter.

4. At the options list select (3) Delete partitions, and Enter.

5. Type in <1>, which is 'Delete primary DOS partition', from the choices given, and Enter.

6. At the warning, select (1), the partition to be deleted, and Enter.

7. At the prompt 'Enter volume label' hit Enter for none, if the partition (volume) has no name in the list. if it has a name, such as WinXP - that whoever installed the partition must have named it as - then type that.

8. At the prompt 'Are you sure?', do not attempt to type in 'I don't really know'; change (N) to (Y) and Enter. The partition is deleted. Hit Esc.

9. From the options displayed, select (1) Create primary DOS partition, and Enter.

10. Click (1), for Create primary DOS partition. 'Verifying drive integrity' runs, showing the percentage completed. 

11. At the prompt 'Do you wish to use the maximum available size and make the partition active?' select (Y) or (N). For the usual single partition, for one OS only, select (Y). If you want to install two OSs or a data partition, and therefore need two partitions, select (N); drive integrity checking runs again (this is an 'issue').

12. If you have chosen multiple partitions, then at the request, enter the partition size for the the first partition (e.g. 50%) and Enter. The partition is created.

13. Hit Esc. Select (2) Select active partition, and Enter.

14. Enter the number of the partition you wish to make active: (1), and Enter.

15. Hit Esc. Hit Esc again. Now reboot the PC, with the Boot Disc still in.

16. Select (1) Start PC with CD-ROM support, and Enter.

17. At the prompt, type <format c:> and Enter. If you have done one partition already, and are doing a second partition, it will be <format d:>. Note that with all these commands, they must be PRECISELY right or nothing will happen. For instance in the first command given, there is a space between format and c.

18. At the warning and prompt 'Proceed with formatting?', type (Y) and Enter. Formatting of the partition starts, with the percentage completed visible.

19. At the prompt 'Enter volume label', hit Enter for none, or type in a label. Use for example W2K for a Windows 2000 partition, XP ditto, or DATA for a data partition. This helps to identify the partition in a list.
At this point, if installing Windows 2000 from a non-bootable CD (eg the Retail Box CD), remove the W98 boot disc, insert W2K boot disc #1, and insert the W2K CD-ROM. Reboot. Continue with the W2K installation as prompted. The setup is automatic, with choices given for language, keyboard layout etc.
20. At the prompt, type <e:\> and Enter. The prompt changes to E:\.

21. Insert the W98 CD in your CD-ROM drive.

22. Type <setup> and Enter. If fault messages come up, try changing the drive letter that you typed in at step 20. to d, and if that doesn't work, then every letter through to h or even higher if you have multiple drives (CD, Zip etc) and partitions. It doesn't matter if you type something in upper or lower case (D or d), since FDISK cannot recognise the difference.

23. At the prompt 'Setup is now going to perform......' hit Enter. Scandisk runs, and all being well, terminates quickly.

24. Type <x> for Exit. The Windows 98 splash screen comes up.

25. Hit 'Continue', and the CD installation starts. Remove the floppy disc now.
Note: there is no need to use the <sys /c> command with this procedure.
When the OS installation is finished 
1. Immediately defrag the drive, as it starts out badly fragmented by the installation routine, which doesn't correct it. Marvellous.

2. Make a new boot disc!
Booting from a CD
FDISK is also on the Windows CDs, in uncompressed format in order to be used directly from the CD; plus the system files and drivers from the boot floppy. In other words, you might be able to boot from the Windows CD and proceed from there. If you do this, it's easier to use than the floppy disc method as: you're eliminating one stage; it's easier to use; it's faster. You can also make a bootable CD, or buy one / download one ready-made for this purpose.
There are however some problems with this, otherwise it would be the perfect solution:
1. Not all PCs or laptops can boot from a CD.
2. Not all Windows CDs are bootable.
3. You will need to enable this in the BIOS, as often it is disabled.
4. Not all BIOS ATAPI drivers work on all CD drives. Obviously this shouldn't be a problem on a standard machine, but if it has been repaired or upgraded it might be.
>1: All new equipment has the ATAPI drivers in BIOS to enable this, so all recent machines can boot from a CD. Obviously, you need CD-ROM drivers available, when the hard drive is bare, in order to access a CD; in the past these were often not present in the BIOS therefore you could not boot from a CD, but they are in all new ones. ASPI drivers are for SCSI arrays, and therefore not needed for the vast majority of machines. Unfortunately, many of us are still using older equipment that doesn't have the ATAPI drivers in the BIOS, so this option is not available to us. From about 2000, all PCs had an ATAPI-enabled BIOS.
Although the boot floppy loads a set of ATAPI drivers, they do not work on all CD drives.
>2: Not all Windows CDs are bootable (in other words you can't boot up without an OS installed or a floppy boot disc, in order to install the OS or get out of trouble). This is, strangely, one of the few advantages of an OEM CD: it is bootable. The Retail Boxed versions aren't (or weren't in the past, from W95 thru W2K). An OEM CD, by the way, is for original equipment manufacturers and retailers to 'package' with their PC sales; it has no box or fancy packaging, and also no warranty with Microsoft. For problems, refer to your dealer. A Retail version comes in a box, and has a warranty with MS – but can't be booted from. Don't ask me why. This is an important point, and one on which a lot of 'experts' are confused, so it's well worth repeating in Very Large Letters:
>3: The boot device or drive is enabled / disabled in the BIOS. If you have a CD which you think is bootable, but the system ignores it on boot-up and hangs due to an incomplete C-Drive, then go into your BIOS options at boot-up and change the settings. You will need to hold down a certain key during the boot sequence, to boot into the CMOS settings (another word for BIOS). This key is different according to the various manufacturers, but you can try Del, F8, or Space. If no joy, then RTFM (Read The Manual). You are not looking to boot into the Safe Mode menus, if this comes up with one key, so reboot and try another key.

To reboot while in pre-OS mode like this, hit Cntrl+Alt+Del (the Control and the Alt and the Delete key at the same time).
When you get to the CMOS settings, go to Main Settings or similar, which will probably be the first page. Look for First Boot Device: it should be A-Drive, the floppy drive. Change the Second Boot Device to D-Drive, your CD-ROM drive (or the appropriate letter if for some reason D is incorrect – perhaps if you have additional drives). Third Boot Device becomes C-Drive, your hard drive. Now Save and Exit. The machine should now reboot and recognise your CD drive.
>4: Not all ATAPI drivers work on all CD drives, though obviously this shouldn't be a problem on a standard machine; if it has been repaired or upgraded it might be.
The boot drive sequence is important, and it may not accord with other advice encountered. The sequencing means that on boot-up the machine looks first for a valid OS in the floppy drive, then the CD drive, then the hard drive; which is what you want. You will however need to ensure that the floppy and CD drives are empty during normal boot-ups, otherwise the machine will try to boot from them. Personally I prefer this rather than having to alter BIOS settings every time I want to do anything on the machine.
Floppy Drives in the 21st Century
They may seem an anachronism, but whenever you present your machine with a seemingly-insoluble problem to the poor old engineer, he'll hope and pray that it has an FD. If not, it just costs you more in the end. Simple. Just think of it as the machine's built-in screwdriver.
Avoid all-USB machines, and DVD / CD drive-only machines, if you want less problems. If you don't care what problems cost to resolve, and you can leave it all to someone else and pay the bill presented without quibbling about the cost or the time it took, then don't worry.
You will eventually find that trying to repair a corrupt or faulty Windows OS is a lost cause. Just bite the bullet and re-format: it cleans everything out. Let's hope you had everything of value backed up before Windows went down; and don't forget to do so before re-formatting, if you have the option.

Tip: use Acronis True Image - you can re-install a clean new OS and the apps and the data in a jiffy: a one-shot new working drive.
Extremely Useful Bit Of Information: if, after playing around installing various OSs, half-deleting them, repairing OSs, using all sorts of different boot discs, and so on, you're left with a 'ghost' OS which causes the boot sequence to stop and give you a choice of operating systems to start up – which aren't actually there in reality – here's a fix: download Acronis OS Selector 5.0 Special Edition (this is the 'Lite' / free / restricted version) from www.acronis.com; it's a free download. Install it and select 'Make default and boot' for your main (and only) OS. The other ghost/s will disappear and the PC will boot straight through as normal. You won't actually know that Acronis is on there (though you can see its program folder Bootwiz in Program Files, and open it via Start - Programs as per usual, if you need to).
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This step-by-step guide to FDISK was written a long time ago. However I still use FDISK by preference, so the concept is still valid. It is also starting to become even more used as repair techs often need to boot into DOS to repair serious virus damage, which is getting worse year by year.

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