The First Hard Drive
Fifty disks, one ton, five million characters.
On 14 September 1956 IBM announces the 350 disk storage unit, the first disk drive: fifty 24-inch disks spinning at 1,200 rpm, holding 5 million characters (about 3.75 MB), weighing about a ton and leased as part of a system for $3,200 a month. The basic layout of a hard drive has barely changed since.
Open in interactive timeline →Key Numbers
- Capacity
- 5 million characters (3.75 MB)
- Disks
- Fifty, 24-inch
- Speed
- 1,200 rpm
- Weight
- About one ton
Verified Facts
- The IBM 350 disk storage unit, the first disk drive, was announced as part of the IBM 305 RAMAC computer on 14 September 1956. RAMAC stood for Random Access Method of Accounting and Control.
- It stored 5 million 6-bit characters (3.75 MB) on fifty 24-inch disks spinning at 1,200 rpm, with a transfer rate of 8,800 characters per second.
- The unit weighed about a ton, had to be moved with forklifts and was often shipped by cargo plane. The RAMAC 305 system with the 350 leased for $3,200 a month.
- IBM's marketing department resisted a bigger drive because it did not know how to sell that much storage; a double-capacity version came in 1959.
Myth vs. Reality
Myth:
Reality: It held 5 million 6-bit characters, which is about 3.75 MB in today's 8-bit bytes.
Frequently Asked Questions
What was the first hard drive?
The IBM 350 disk storage unit, announced on 14 September 1956 as part of the IBM 305 RAMAC computer.
How much did the first hard drive hold?
5 million 6-bit characters, about 3.75 MB, on fifty 24-inch disks.
How big was the first hard drive?
It weighed about a ton and had to be moved with forklifts.
Sources & Further Reading
Cite This Page
AskHistoryAI. “The First Hard Drive.” AskHistoryAI — Interactive Timeline of Everything. Updated 2026-10-08. https://askhistoryai.com/event/sv-ibm-ramac/
Every fact on this page is checked against the published fact ledger and methodology; sources are listed above.