RA90
| Industry | Computer hardware |
|---|---|
| Founded | November 7, 1957 in Massachusetts, United States |
| Headquarters | Maynard , United States |
| Products | Disk drives, computers, storage arrays |
The RA90 disk drive represented Digital Equipment Corporation's initial adoption of "thin film" technology, which replaced the previous "oxide" disk design that utilized aluminum surfaces coated with gamma ferric oxide particles. Launched in 1988, the RA90 offered a storage capacity of 1.2GB and operated through controllers that supported the Mass Storage Control Protocol.
Overview
The RA90 not only introduced thin film technology but also marked DEC's foray into Storage Arrays with the debut of the SA600 Storage Array. This array was available with either 4 or 8 drives, providing total capacities of 4.8GB or 9.7GB respectively. Additional configurations included the SA550 and SA650 Mixed Storage Arrays, which integrated RA70s with RA82s in the SA550, and RA90s in the SA650. The SA482 model consisted exclusively of RA82 drives. By upgrading to 1.5GB RA92 drives, the SA800 Storage Array achieved a maximum capacity of 12GB.
History
Thin film disk technology was initially developed by Ampex Corporation in California during the late 1960s, with the first thin film disks manufactured at their San Jose facility by 1982. Following financial difficulties at Ampex, Marv Garrison—a key figure in thin film disk development—joined Digital's Colorado Springs plant. A significant industry discussion revolved around whether to apply the magnetic layer by sputtering or plating; both DEC and Ampex opted for plating despite its higher expense, although sputtering eventually became the preferred method due to greater reliability. The RA90 experienced delays in reaching an acceptable mean time before failure (MTBF), which allowed competitors to gain market advantage by offering smaller drives with higher capacity and improved dependability. Production of RA90 units took place at Digital’s extensive Colorado Springs facility, while disk manufacturing occurred in Tempe, Arizona.
Technology
Thin film disks consisted of a metallic coating applied over an aluminum base that had been pre-treated with a nickel-phosphate alloy to strengthen the otherwise soft aluminum substrate. This technology permitted significantly higher storage densities by enabling a much thinner magnetic layer compared to traditional disks coated with urethane binders. The magnetized domains on thin film disks were rectangular in shape, allowing them to be positioned more closely without causing interference, thus enhancing data density and ensuring the integrity of stored information.
Other RA disk drives
The DEC RA series also encompassed other models such as the removable RA60 and several Winchester-type drives including the RA70, RA71, RA72, RA73, RA80, RA81, RA82, and RA92.
External links
- Oral History of Grant Saviers recorded 17 May 2011, page 42 discusses RA90