The RA90 disk drive
was the first
Digital Equipment Corporation
Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president unt ...
drive to be based on "thin film" technology. Prior to the RA90 all Digital disk drives used "oxide" disks, which were an
aluminum disk coated with a polyurethane binder resin containing gamma ferric oxide particles as the recording medium. The 1988-released RA90, which held 1.2GB, was used with controllers implementing the
Mass Storage Control Protocol
The Mass Storage Control Protocol (MSCP) is a protocol that was designed by Digital Equipment Corporation of Maynard, Massachusetts for the purposes of controlling their high-end mass storage options.
First implemented in the HSC50 hierarchical ...
.
Overview
The RA90 disk drive, in addition to being DEC's first step into ''thin film'' technology, also introduced another first for ''DEC''": ''Storage Arrays''. Their first was the ''SA600 Storage Array'', which had 4 or 8 drives. Other models were the SA550 and SA650 ''Mixed Storage Array''s,
combining RA70s with RA82s (SA550) or RA90s (SA650).
[ The SA482 used just RA82s instead of RA90s.
Replacing the 1.2GB RA90s with 1.5GB RA92s, an ''SA800 Storage Array'' held 12GB.
]
History
The technology was pioneered by Ampex Corporation
Ampex is an American electronics company founded in 1944 by Alexander M. Poniatoff as a spin-off of Dalmo-Victor. The name AMPEX is a portmanteau, created by its founder, which stands for Alexander M. Poniatoff Excellence.AbramsoThe History ...
in Redwood City, California
Redwood City is a city on the San Francisco Peninsula in Northern California's Bay Area, approximately south of San Francisco, and northwest of San Jose. Redwood City's history spans its earliest inhabitation by the Ohlone people to being a ...
based on a slow motion and still frame video recorder the company had developed in 1967. In 1982 Ampex built a factory in San Jose, California
San Jose, officially San José (; ; ), is a major city in the U.S. state of California that is the cultural, financial, and political center of Silicon Valley and largest city in Northern California by both population and area. With a 2020 popul ...
that produced the first thin film disks. When Ampex ran into financial difficulties, the pioneer of thin film disk technology, Marv Garrison (now deceased) left Ampex to join Digital
Digital usually refers to something using discrete digits, often binary digits.
Technology and computing Hardware
*Digital electronics, electronic circuits which operate using digital signals
**Digital camera, which captures and stores digital i ...
's thin film disk facility in Colorado Springs
Colorado Springs is a home rule municipality in, and the county seat of, El Paso County, Colorado, United States. It is the largest city in El Paso County, with a population of 478,961 at the 2020 United States Census, a 15.02% increase since ...
. A long debate ensued at the time as to whether the magnetic layer on thin film disks ought to be sputtered or plated. Ampex and Digital settled on plating. However, in spite of the higher capital equipment investment required by sputtering, the latter proved in the long term to be the more reliable technology and remains as the industry standard today. It took Digital a long time to achieve adequate MTBF (mean time before failure) performance standards for the RA-90, which delayed its time to market sufficiently to be undersold by competitors, who, by then, had introduced smaller form factors (smaller disks) at higher capacities and greater reliability. RA-90 drives were built at Digital's 1 million square foot (93,000 m²) facility in Colorado Springs and the disks were made in Tempe, Arizona
, settlement_type = City
, named_for = Vale of Tempe
, image_skyline = Tempeskyline3.jpg
, imagesize = 260px
, image_caption = Tempe skyline as se ...
.
Technology
Thin film disks consisted of a metallic coating applied onto an aluminum substrate which had first been coated with a nickel-phosphate alloy (non magnetic) to add hardness to the soft aluminum substrate. The reason thin film disks could provide higher storage capacity has to do with the physics of magnetic recording. A plated or sputtered magnetic layer could be made much thinner than the coated urethane binder layer. Magnets don't like to be square, but rather rectangular. So, in the thin film one could place the magnetized domains much closer together whilst keeping the overall shape of the domain rectangular. This meant that adjacent magnetized areas of the disk surface could exist without cancelling each other out, or erasing the information recorded on the disk surface.
Other RA disk drives
Other ''DEC'' disk drives in the ''RA'' family were: RA60 (removable), and the RA70/71/72/73/80/81/82/92 (Winchester).
Notes
References
External links
Oral History of Grant Saviers
recorded 17 May 2011, page 42 starts talking about RA90
{{DEFAULTSORT:Ra90
DEC hardware