IBM 305
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BRL61-IBM_305_RAMAC.jpeg
BRL61-IBM_305_RAMAC.jpeg
IBM 305 at U. S. Army Red River Arsenal
The IBM RAMAC 305 was the first commercial computer that used magnetic disk storage. IBM introduced it on September 4, 1956. RAMAC stood for "Random Access Method of Accounting and Control." The 305 was one of the last vacuum tube computers that IBM built. The IBM 350 disk system stored 5 million characters. It had fifty 24-inch diameter disks. Two independent access arms moved up and down to select a disk and in and out to select a recording track, all under servo control. Several improved models were added in the 1950s. The IBM RAMAC 305 system with 350 disk storage leased for $3,200 per month. More than 1000 systems were built. Production ended in 1961 and the 305 was withdrawn in 1969.
External link
- IBM Archives on the 305 (http://www-1.ibm.com/ibm/history/exhibits/storage/storage_PH0305.html)
- IBM 305 RAMAC Data Processing System (http://ed-thelen.org/comp-hist/BRL61-ibm03.html#IBM-305-RAMAC)