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IBM and Hitachi Microdrive harddisk drives, with an American quarter for size comparison.
IBM and Hitachi Microdrive harddisk drives, with an American quarter for size comparison.
Inside a 1-inch Seagate drive
Inside a 1-inch Seagate drive

Microdrive is a registered trademark for miniature, 1-inch hard disks produced by IBM and Hitachi. These rotational media storage devices were designed to fit in CompactFlash (CF) Type II slots. The release of similar drives by other makers led to them often being referred to as "microdrives" too. By 2015, Microdrives were viewed as obsolete, having been overtaken by solid-state flash media in read/write performance, storage capacity, durability, and price.


Prior to the 1-inch Microdrive, a 1.3-inch HDD was developed and launched in 1992 by HP with a capacity of 20 MB. These units weighed about 28 g (1 oz), with dimensions of 2.0" × 1.44" × 0.414" (50.8 mm × 36.5 mm × 10.5 mm) and were the physically smallest hard drives in the world before the Microdrive.

In 1999, IBM launched the first generation 1-inch Microdrive with storage capacities of 170 MB and 340 MB.[1] The physical dimensions of Microdrive were 1.65" × 1.42" × 0.197" (42.0 mm × 36.0 mm × 5.0 mm) and conformed to CompactFlash Type II card standard. A second generation of Microdrive was announced by IBM in 2000 with increased capacities at 512 MB and 1 GB. Following the merger of IBM and Hitachi HDD business units, Hitachi Global Storage Technologies continued the development and marketing of the Microdrive. In 2003, 2 GB and 4 GB models were announced[2] by Hitachi, followed by 6 GB capacity model in 2005.

Seagate 2.5 GB 1" CF drive
Seagate 2.5 GB 1" CF drive

In 2004, Seagate launched 2.5 and 5 GB hard disk drives in the same small physical form-factor as IBM Microdrive, and referred to them as either 1-inch hard drives or CompactFlash hard drives due to the trademark issue. These drives were also commonly known as the Seagate ST1. In 2005 Seagate launched an 8 GB model. Seagate also sold a standalone consumer product based on these drives with a product known as the Pocket Hard Drive. These devices came in the shape of a hockey puck with an integrated USB 2.0 cable.

In 2003-07-16, a Chinese manufacturer called GS Magicstor, Inc. (subsidiary of GS Magic, Inc.) announced it had produced 1-inch hard disk drive with capacity of 2.4GB at the beginning of the year 2003,[3] originally marketed as an alternative to Microdrive by Hitachi Global Storage Technologies.[4] It was to be followed by 2.2 and 4.8GB 1-inch HDD that was unveiled in 2004 International CES, with 0.8-inch HDD.[5][6][7] In 2004-12-28, Hitachi Global Storage Technologies announced it had filed lawsuit against GS Magicstor, Inc., GS Magic, Inc., and Riospring, Inc. for infringement of multiple Hitachi GST's patents relating to hard disk drives,[8][9] after GS Magic Inc. had started promoting mini-HDD (small form factor hard disk drive).[10]

As of July 2012, there are no known manufacturers of 1-inch form-factor harddisk drives. Hitachi had also stopped production of its trademarked Microdrive product.

Microdrive models by timeline

A pair of 1gb IBM Microdrives, with a PCMCIA/Cardbus adapter
A pair of 1gb IBM Microdrives, with a PCMCIA/Cardbus adapter

Date of release of large sizes.

1999: 170 megabyte, 340 megabyte (IBM)
2000: 512 megabyte, 1 gigabyte (IBM)
2003: 2 gigabytes, 4 gigabytes (Hitachi)
2004: 2.5 and 5 gigabytes (Seagate)
2005: 6 gigabytes (Hitachi), 8 gigabytes (Seagate)
2006: 8 gigabytes (Hitachi)



The iPod Mini (1st gen shown) uses a Microdrive to store data.
The iPod Mini (1st gen shown) uses a Microdrive to store data.

Microdrive models by manufacturer

IBM Microdrive

Several physical examples of Microdrives are held by the Computer History Museum.[14][15]

Hitachi Microdrive

IBM and Hitachi models were fitted with 128 KB of cache memory.

GS Magicstor

Seagate ST1

These Seagate models were fitted with 2 MB of cache memory.

Sony Compact Vault



Western Digital

See also


  1. ^ IBM ships the world's smallest hard drive
  2. ^ World's Smallest Hard Drive Now Bigger: 4GB on a One-Inch Disk
  3. ^ The Meeting of Productions Announcement
  4. ^ David Chu Reshapes 1" HDD Industry
  5. ^ GS Magicstor Announces 1-Inch Hard Drive
  6. ^ Conference highlights high-tech industry
  7. ^ GS Magicstor Inc. unveils groundbreaking 1" HDD at 2004 International CES
  8. ^ Howard French (5 March 2005). "The New York Times > Business > World Business > Whose Patent Is It, Anyway?". China: Retrieved 2012-11-03.
  9. ^ Hitachi Files Patent Infringement Complaint against GS Magicstor Companies
  10. ^ Guizhou Important Technologies News Conference - Focus on mini-HDD
  11. ^ Hitachi Microdrive with PCMCIA advert on box e.g. there
  12. ^ SanDisk introduces the world’s highest capacity card for professional photographers - the 16-gigabyte SanDisk Extreme III CompactFlash
  13. ^ Corsair launches 16GB Flash Voyager drive
  14. ^ "IBM 1 GB Microdrive DSCM-11000" Computer History Museum Catalog Number 102662593
  15. ^ "IBM family of Microdrives", Data sheet G225-6801-02
  16. ^ WD Passport Pocket Drive