According to this message, which circulates via email, blogs and online communities, an attached photograph depicts an early, and very large, hard disk drive designed to be used with IBM’s 305 RAMAC computer, which was launched in 1956.





The photograph shows the hard disk drive component along with the large commercial aircraft being used to transport it.

The photograph is genuine, and the information in the message is factual. Another photograph of one of the disk storage units can be viewed on IBM’s archives website, along with the following caption:

The IBM 350 Disk Storage Unit was rolled out in 1956 to be used with the IBM 305 RAMAC to provide storage capacities of five, 10, 15 or 20 million characters. It was configured with 50 magnetic disks containing 50,000 sectors, each of which held 100 alphanumeric characters.

Yet another shot of the disk drive is included in an article discussing the 305 RAMAC published on the CED Magic website. The article explains:

IBM introduced the 305 RAMAC computer on September 13th, 1956, which was the first computer to include a disk drive named the IBM 350 Disk File. Prior to this magnetic computer storage had consisted of core memory, tape, and drums. The magnetic disk was seen as a replacement for the magnetic drum for the same reason 78 RPM Records eventually replaced Edison cylinders- more storage with less space. The 350 Disk File consisted of a stack of fifty 24″ discs that can be seen to the left of the operator in the above picture. The capacity of the entire disk file was 5 million 7-bit characters, which works out to about 4.4 MB in modern parlance. This is about the same capacity as the first personal computer hard drives that appeared in the early 1980s, but was an enormous capacity for 1956. IBM leased the 350 Disk File for a $35,000 annual fee.

The photograph certainly provides a graphic example of how much computer technology has developed over the last fifty years. Hard drives are now available that provide several terabytes of storage.

And of course, modern hard drives are only a tiny fraction of the size of IBM’s early disk storage units. In fact, even the smallest capacity memory sticks and camera storage cards now available provide hundreds of times more storage space than the 305 RAMAC’s storage unit.









1956 Hard Disk Drive – Disk Storage Unit for 305 RAMAC Computer was last modified: by

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