One month shy of 50 years ago

[mdlbear]

Early IBM disk storage - Wikipedia, the free encyclopedia

The IBM 350 was part of the IBM RAMAC 305, the computer that introduced disk storage technology to the world on September 4, 1956. RAMAC stood for "Random Access Method of Accounting and Control." The 350 stored 5 million characters (about 5 megabytes). It had fifty 24-inch diameter disks with 100 recording surfaces. Each surface had 100 tracks. The disks spun at 1200 RPM. Data transfer rate was 8,800 characters per second. 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. A third arm was added as an option. Several improved models were added in the 1950s. The IBM RAMAC 305 system with 350 disk storage leased for $3,200 per month. The 350 was officially withdrawn in 1969.

The 350's cabinet was 60 inches (approx. 1,52 meters) long, 68 inches (approx. 1,72 meters) high and 29 inches (approx. 74 centimeters) deep. IBM had a strict rule that all its products must pass through a standard 29.5 inch (approx. 75 centimeters) doorway. Since the 350's platters were mounted horizontally, this rule presumably dictated the maximum diameter of the disks.

Comments

[finagler.livejournal.com]

Let's see, that's about 42.25 bytes / in³, and a 500 GB drive today is around 5970 Meg / in³, for a factor of 1.4 x 10⁸ in 50 years. That means a doubling of storage density about every 20 months... sounds about right.