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1 GB IBM Microdrive
Media typeHard disk drive
Capacity170 MB - 16 GB
Developed byIBM, Hitachi
Manufactured by
Dimensions42.0 mm × 36.0 mm × 5.0 mm
UsagePortable devices, notebooks
ReleasedSeptember 9, 1998
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 2010, 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 nicknamed the "Kittyhawk" was developed and launched in June 1992 by HP with a capacity of 20, then later 40 MB. These units weighed about 28g (1oz), with dimensions of 2.0" × 1.44" × 0.414" (50.8mm × 36.5mm × 10.5mm) and were the physically smallest hard drives in the world before the Microdrive. The Kittyhawk was a failure however, and didn't last long in the market.

Development & Introduction

The idea of the Microdrive was created by IBM researcher Timothy J. Reiley who was working at the Almaden Research Center in San Jose. He wanted to create a small form factor hard disk drive with high capacity storage that would be used for mobile devices, after working on a project to look at Micromechanics.[1] Originally Timothy planned for the drive to use Microelectromechanical systems for parts of the drive such as the spindle motor and head actuator. Thomas R. Albrecht, another researcher, collaborated with Timothy to design and create the drive. Thomas changed the drive technology to miniaturized conventional technologies instead due to the increased technical risk and costs of using Microelectromechanical systems.[2]

The leader of mobile drive development at IBM's Fujisawa facility at the time, Hideya Ino, highly sought the potential of a 1-inch disk drive. He had a team collaborate with the IBM researchers to create working prototypes. Those prototypes where then used to persuade product planning and marketing teams to support the project. Two notable people from the Japan development team were Mitsuhiko Aoyagi and Kenji Kuroki, who contributed to launching the product line. Bill Healey and John Osterhout worked at the storage technology division in San Jose and were responsible for the business development and marketing of the Microdrive.

In September 1998, IBM announced the Microdrive.[3] It was advertised as being about the size of a large coin, weighing less than an AA battery, and the capacity of over 200 floppy disks. The Microdrive was expected to be available by mid-1999.[4]

In June 1999, IBM launched the first generation 1-inch Microdrive. It had storage capacities of 170MB and 340MB at a price of $499. The physical dimensions of Microdrive were 1.65" × 1.42" × 0.197" (42.0mm × 36.0mm × 5.0mm) and conformed to CompactFlash Type II card standard. A second generation of Microdrive was announced by IBM in June 2000 with increased capacities at 512MB and 1GB, with the 512 MB model costing $399 and the 1 GB model costing $499.[5][6]

Following the merger of IBM and Hitachi HDD business units, Hitachi Global Storage Technologies continued the development and marketing of the Microdrive. In 2003, 2GB and 4GB models were announced by Hitachi.[7][8] The 4 GB model was first available on February 20, 2004 for a price of $499.[9] This was followed by a 6GB capacity model in February 2005 for a price of $299, with the 4 GB model dropping to $199.[10][11] Hitachi additionally planned an even smaller 1-inch hard drive with a capacity of 8-10 GB under the code-name "Mikey" for late 2005 with a weight of 14 grams and a size of 40 mm × 30 mm × 5 mm.[12][13]

By 2007, sales and profit of the Microdrive were dwindling so Hitachi discontinued production of 1 inch hard disk drives. Sales of 1-inch drives were only about 3,000 in a three-month period in 2007, while 560,000 units of 1-1.8-inch drives were sold throughout July to September 2007. Hitachi wanted to shift over to bigger 2.5 and 3.5-inch hard disk drives, rather than retain focus on the small hard disk drive business.[14]


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

In 2004, Seagate launched 2.5 and 5GB 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 8GB 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.

Seagate launched their 6 GB mini drive on the same day as Hitachi, in February 2005.[15]

Western Digital

In early 2005 Western Digital announced they would be joining the mini hard drive market with their own drives. These would be available by the second half of 2005 and reach capacities up to 6 GB.[16]

Western Digital launched a 6 GB external USB 2.0 microdrive as a part of the Passport Pocket brand in March 2006. This was made as a competitor to the Seagate Pocket Hard Drive. The unit had 2 MB of cache, 11 ms seek, spun at 3,600 RPM, and was 60 × 45 × 9 mm. The price for the unit was $130 upon release. [17]

GS Magicstor

On July 16, 2003, 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, originally marketed as an alternative to Microdrive by Hitachi Global Storage Technologies. 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. On December 28, 2004, 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, after GS Magic Inc. had started promoting mini-HDD (small form factor hard disk drive).


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.

June 1999: IBM releases 170, 340 MB Microdrives
June 2000: IBM releases 512 MB, 1 GB Microdrives
2003: 2 gigabytes, 4 gigabytes (Hitachi)
2004: 2.5 and 5 gigabytes (Seagate)
February 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.[20]

Hitachi Microdrive

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

GS Magicstor

Seagate ST1

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

Sony Compact Vault



Western Digital

See also


  1. ^ Costlow, Terry (7 July 1999). "One inch no cinch for IBM storage gurus". EE Times. Retrieved 12 August 2022.
  2. ^ "1999: IBM Microdrive, First One-Inch HDD" (PDF). Retrieved 12 August 2022.
  3. ^ Farrance, Rex (11 September 1998). "IBM unveils smallest-ever hard drive". CNN. Retrieved 27 May 2022.
  4. ^ "IBM shows tiny disk drive; New microdrive, size of a large coin, is aimed at portable electronic devices". CNN. 9 September 1998. Retrieved 27 May 2022.
  5. ^ "IBM makes 512MB and 1GB Microdrive official". Digital Photography Review. 21 June 2000. Retrieved 27 May 2022.
  6. ^ "IBM unveils 1GB mini drive; New Microdrive triples capacity of miniature hard disk drive for portables". CNN. 20 June 2000. Retrieved 27 May 2022.
  7. ^ "HITACHI GLOBAL : News Releases from Headquarters : Jan 6, 2003". Retrieved 2022-05-27.
  8. ^ Bennett, Amy (26 August 2003). "Hitachi to ship 2GB, 4GB Microdrives this year". Computerworld. Retrieved 27 May 2022.
  9. ^ Frauenheim, Ed (11 February 2004). "IBM to ship 4GB microdrive; Big Blue unveils tiny hard drive made by Hitachi, targeting laptop users". ZDnet. Retrieved 27 May 2022.
  10. ^ Williams, Martyn (23 February 2005). "Hitachi slashes Microdrive prices, debuts 6GB model". Computerworld. Retrieved 27 May 2022.
  11. ^ "Hitachi 6GB Microdrive sells for just $299". Digital Photography Review. 24 February 2005. Retrieved 27 May 2022.
  12. ^ Kanellos, Michael (7 January 2005). "Hitachi drives get bigger--and smaller; Company cuts some fat from its diminutive devices, to squeeze them into cell phones, while upping the capacity of PC drives". Cnet. Retrieved 27 May 2022.
  13. ^ "Hitachi Global Storage Technologies Announces New Hard Drives". Videomaker. 7 January 2005. Retrieved 27 May 2022.
  14. ^ "Hitachi to phase out small hard drives". Reuters. 4 January 2008. Retrieved 27 May 2022.
  15. ^ Hachman, Mark (23 February 2005). "Seagate, Hitachi Announce 6-GB 1-Inch Drives". Extreme Tech. Retrieved 27 May 2022.
  16. ^ Shim, Richard (19 January 2005). "Western Digital to enter minidrive arena; Hard drive maker plans to start shipping a one-inch product in the second quarter". Cnet. Retrieved 27 May 2022.
  17. ^ Smith, Tony (29 March 2006). "WD unveils 6GB pocket drive". The Register. Retrieved 27 May 2022.
  18. ^ Hitachi Microdrive with PCMCIA advert on the box:
  19. ^ Corsair launches 16GB Flash Voyager drive
  20. ^ "IBM family of Microdrives", Data sheet G225-6801-02