The world’s first hard disk drive was the IBM Model 350 Disk File and it appeared in 1956. It consisted of fifty 24″ disks which could hold up to 3.75MB of data. It was a huge device, weighing over a ton and had to be transported by fork lift truck.
The IBM Model 350 Disk File hard disk couldn’t be bought, instead it was leased to customers along with the IBM’s RAMAC 305 computer (of which it was a part) at an average cost of $3200 per month, equivalent to approximately $25,000 in 2014.
Today the US patent for the RAMAC is considered to be the defining patent for hard disk drives, but it almost never saw the light of day. The IBM Board of Directors were so fearful that the 350 would destroy IBM’s lucrative punch card business that they cancelled the entire project. It was only because of IBM’s chairman at the time that the project was eventually reintroduced and pushed through.
Here’s a fascinating video showing IBM’s RAMAC 305 and Model 350 Disk File in operation.