The first hard disk drive released by IBM was called the IBM 350 disk storage unit. It was revolutionary for its time, offering a major leap forward in data storage capacity compared to previous magnetic drum storage devices. In an era when most computers still relied on punch cards and magnetic tape for data storage, the IBM 350 disk drive provided an unprecedented level of rapid access to vast amounts of data. But by today’s standards, that first IBM hard drive was minuscule in terms of capacity.
The Specifications of the IBM 350 Disk Drive
The IBM 350 disk storage unit was first introduced in 1956. It had a total formatted capacity of 3.75 megabytes (MB), which was enormous for the era. The drive enclosed fifty 24-inch diameter disks containing a total of 100 recording surfaces. Each disk surface provided 30,000 bytes of data storage.
To put this capacity into perspective, the data storage needs of early computers were much smaller than today. In 1956, this drive provided enough capacity to hold the equivalent of around 64,000 punched cards storing 80 bytes each. Programs and data were stored on stacks of punched cards at the time. The IBM 350 drive provided the capacity of a small room filled with shelves of card stacks in a device the size of a refrigerator.
A Major Leap in Capacity for the Time
Prior IBM data storage devices that the 350 drive replaced were based on magnetic drum memory. These storage devices had far less capacity. For example, the IBM 305 RAMAC drum memory system could store roughly 4,000 blocks of data containing 100 alphanumeric characters each. This equates to just 400,000 bytes or 0.4 MB of capacity.
By offering almost 10 times the capacity of prior IBM storage systems, the 350 disk drive represented a major advancement. It provided the ability to instantly access large databases that previously required laborious physical searching through boxes of punched cards. The random access capabilities of the 350 drive were also a vast improvement over sequential access tape drives.
Minuscule Compared to Today’s Hard Drives
While the IBM 350 drive offered groundbreaking capacity for 1956, its 3.75 MB size seems impossibly small from today’s perspective. By contrast, modern consumer hard disk drives provide terabytes of capacity.
To illustrate just how much storage capacity has increased, a single terabyte (TB) is equal to 1,000 gigabytes (GB), which is 1,000,000 MB. So a 1 TB drive today offers about 267,000 times the maximum capacity of the IBM 350 drive. Even pocket-sized USB flash drives today commonly provide 64 GB of capacity, which is over 17,000 times greater than the first IBM drive.
Tech Specs of the IBM 350 Disk Storage Unit
Here are some key technical specifications to provide an overview of the first IBM hard disk drive:
- First sold: September 1956
- Storage capacity: 3.75 MB (100 surfaces with 30,000 bytes each)
- Number of disks: 50 (24-inch diameter disks)
- Areal density: 2,000 bits/inch2
- Disk rotational speed: 1,200 RPM
- Data transfer speed: 8,800 bytes/second
- Average seek time: 600 milliseconds
- Interface: Parallel
- Physical size: Approximately 65 inches wide x 68 inches deep x 30 inches high
- Weight: About 1 ton
While very slow and minuscule in capacity by modern standards, the seek time, transfer rate, and capacity represented significant breakthroughs in data storage when this drive was introduced.
Comparison of IBM 350 Specs to Modern Hard Drives
To demonstrate just how far hard drive tech has come since 1956, here is a comparison of the IBM 350 drive specs versus a typical modern desktop 3.5-inch hard disk drive:
| Spec | IBM 350 Disk Drive | Modern 3.5-inch HDD |
|---|---|---|
| Formatted Capacity | 3.75 MB | 1 TB |
| Data Transfer Rate | 8,800 bytes/sec | Up to 210 MB/sec |
| Average Seek Time | 600 ms | 10 ms |
| Size | 65 x 68 x 30 inches | 4 x 5.8 x 1 inches |
| Weight | About 1 ton | About 1/10 pound |
This comparison highlights just how dramatically hard drive technology improved over the decades following the IBM 350 drive in terms of capacity, performance, size and weight. While a landmark data storage achievement for its era, the specs seem shockingly archaic from a modern perspective.
The IBM 350’s Impact and Legacy
The IBM 350 disk drive completely transformed data storage and processing for computers of the late 1950s and early 1960s. By providing rapid random access to large databases of information, it enabled new capabilities in business data processing, scientific and engineering calculations, and other applications. The IBM 350 drive proved the feasibility of disk storage systems and pioneered their use in commercial data processing.
This drive was a major milestone in the history of data storage technology. While the fixed hard disks it used were rapidly replaced by removable disk packs a few years later, the IBM 350 demonstrated the enormous potential of hard disk drives. It paved the way for their ubiquitous use in computers by the early 1960s and established HDDs as a core computer data storage technology moving forward.
All modern hard disk drives can trace their roots back to groundbreaking pioneering work like the IBM 350. So while minuscule and slow by today’s standards, this first disk drive developed by IBM in 1956 was hugely influential and marked the beginning of the hard disk drive revolution. The IBM 350 proved that large amounts of data could be quickly accessed in a random-access manner from a compact device.
Conclusion
In summary, the first hard disk drive developed by IBM was the IBM 350 disk storage unit announced in 1956. This drive contained 50 disks providing a total formatted capacity of 3.75 MB. While extremely small by modern standards, this represented an enormous leap from previous magnetic drum storage devices of the era. The IBM 350 drive pioneered the use of hard disk storage and enabled much faster random access to vast amounts of data than previously possible. This transformed capabilities in business and scientific computing. The IBM 350 marked the beginning of the hard disk drive era, although its capacity was rapidly dwarfed within a few years. All modern hard drives trace their ancestry to pioneering early drives like this model introduced by IBM in 1956. While the specs seem impossibly archaic today, the IBM 350 disk storage unit represented a major milestone in data storage technology at the time.