Fixed Disk

What Does Fixed Disk Mean?

FDISK (short for fixed disk) is a command-line utility used on PCs to perform disk partitioning.


Partitioning divides hard drive space, and other storage media space, into logical drives or partitions and assigns drive letters such as C, D, E, etc. Each logical drive is assigned a letter and has its own maximum storage capacity. Specific and emphatic warnings are given when using this utility, because repartitioning wipes out all data. After partitioning, each partition must be individually formatted.

FDISK also writes the master boot record.

Techopedia Explains Fixed Disk

A DOS FDISK program came with the original Windows 95 OS. It was only capable of creating File Allocation Table (FAT) partitions of FAT12 and FAT16 types. The FAT32 type came with versions of Windows 95B and later. Windows 2000 and later versions did not use FDISK, but instead used a Logical Disk Manager, as well as DiskPart, which were both a part of the Windows OS.

Most personal computers today have hard drives which are partitioned, formatted and have the OS and specific applications already installed. Usually, new computer system hard drives have a single partition addressed by the OS as the logical “C” drive.

FDISK also had some limitations. Applications could not be moved from one partition to another, meaning from one drive letter to another, without uninstalling and reinstalling. A partition could not be deleted without losing all data on that partition, repeating the entire FDISK process again and reformatting the partition. Also, it was usually necessary to create a number of partitions to use the full hard drive capacity.

Some advantages of FDISK were the ability to hide partitions from other users to protect data, its use as a boot manager allowing easy use of more than one operating system and the lack of a requirement to upgrade the BIOS in older computers.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.