Hard disks have been used to store data since the 1950s. Since then, they have gone through many changes and improvements, becoming ever smaller, more reliable and able to store huge amounts of data.
In this article, we look at the history of the hard disk and its main developments over time, from the first magnetic disks to today’s high-capacity drives. We’ll see how these devices were developed, how they evolved and how they shaped the technology we use today.
What is a hard disk?
A hard disk is a data storage device made up of one or more rigid platters, usually aluminum or glass, coated with a magnetic layer. Data is written to and read from them by read/write heads that move over the surface of the spinning platters.
For decades, hard disks were the main storage device in personal computers. Today most new PCs use SSDs, but hard disks are still widely used in servers, NAS systems, external drives and cloud storage. They store all kinds of data: operating systems, programs, documents, music, photos and videos.
A hard disk connects to the computer through an interface, usually SATA (Serial Advanced Technology Attachment) or SAS (Serial Attached SCSI), and is powered by the computer’s power supply or an external adapter. Capacities range from a few hundred gigabytes to tens of terabytes, and read and write speeds also vary from model to model.
As technology advances, hard disk capacities and speeds keep increasing, along with their reliability.
Who invented the hard disk?
The invention of the hard disk was a major milestone in the history of data storage. The first hard disk was developed by an IBM team in San Jose, California, led by engineer Reynold Johnson, in the early 1950s. It was part of the RAMAC system (Random Access Method of Accounting and Control), announced in 1956, and used 50 magnetic disks to store about five million characters, roughly 3.75 MB of data.
It was the first storage device based on magnetic disks and, unlike earlier devices such as magnetic tape, it could access any point on the disk directly (random access). The work of Reynold Johnson’s team was essential to the development of data storage and to the growth of computing in general.
Hard disk technology timeline
The hard disk has come a long way to become what it is today. Its history begins in 1956 and includes several milestones over the years. Here they are:
The first commercial hard disk
The IBM 350, the disk unit of the RAMAC system, was announced by IBM in 1956 and shipped to customers from 1957. It had 50 magnetic disks, 24 inches in diameter, with 50,000 sectors that each held 100 alphanumeric characters. In other words, it stored about 5 million characters (around 3.75 MB).
The first hard disk with air-bearing heads
In 1961, IBM announced the IBM 1301, whose heads flew over the disks on a thin cushion of air (an air bearing) to read and write data.
Compared with the IBM 350, the IBM 1301 was a major step forward in storage, with a much larger capacity.
The removable disk pack drive
The IBM 1311, announced in 1962, was the first hard disk drive to use removable disk packs. Each pack held about 2 million characters, with a higher recording density than earlier drives.
The IBM 1311 was also much smaller than its predecessors. While earlier drives were about the size of a wardrobe, this one was the size of a washing machine.
Eight-inch floppy disks
Alongside hard disks, companies were also looking for a cheap, removable way of storing and transporting data.
At the end of the 1960s, IBM engineers in San Jose developed the eight-inch floppy disk, which only reached the market in 1971.
The first of these disks had a very limited capacity: only about 80 KB.
Microcomputers used for engineering, business or word processing generally had one or more 8-inch floppy disk drives for removable storage.
The sealed hard disk drive
In 1973, IBM introduced the 3340, known as “Winchester”: a hard disk drive whose platters and heads were enclosed in a sealed module, with lubricated platters and lightweight heads.
The drive stood out for its smaller, lighter read/write heads and its design, which allowed them to fly much closer to the surface of the disk.
The Winchester was the first hard disk to work in much the same way as today’s hard disks, and it had twice the data density of IBM’s previous disks.
Floppy disks also evolved: in 1976 the smaller 5.25-inch floppy disk arrived, and in the 1980s the 3.5-inch disk. They were light, practical and portable, but their storage capacity was limited (the most common 3.5-inch disks held 1.44 MB), so several disks were often needed to store larger files.
RAID technology
The idea behind RAID (Redundant Array of Independent Disks) dates back to an IBM patent granted in 1978, and the term itself was coined in 1987 by researchers at the University of California, Berkeley. Its aim is to improve the performance and reliability of storage systems by combining several disks and, in most levels, using redundancy.
RAID uses a set of two or more hard disks, is mainly used in servers and NAS systems, and has two basic goals:
- Increasing the speed of the disk system by splitting data across the disks, known as striping (RAID 0, which has no redundancy);
- Making the disk system more fault-tolerant by copying the data to two disks, known as mirroring (RAID 1).
Even with newer storage technologies, RAID is still widely used thanks to its focus on fault tolerance and speed. Keep in mind, though, that RAID is not a backup.
Hard disk drives for microcomputers
In 1980, Seagate Technology (then still called Shugart Technology) launched the first 5.25-inch hard disk for microcomputers, the ST-506.
The drive used a stepper motor to move the heads and stored 5 MB in total.
The ST-506 connected to the computer through a disk controller, and the interface between controller and drive was derived from Shugart Associates’ SA1000 interface, which in turn was based on the floppy drive interface. This made designing disk controllers relatively easy.
The introduction of IDE and SCSI
In the 1980s, the IDE (Integrated Drive Electronics) interface appeared, later standardized as ATA (Advanced Technology Attachment) and now known as PATA (Parallel ATA).
Its main innovation was integrating the controller into the drive itself.
The first standard, ATA-1, supported drives of up to about 528 MB, with a transfer rate of 8.3 MB/s and a cycle time of 240 ns. Later versions raised the maximum transfer rate to 133 MB/s, and the last standard, ATA/ATAPI-8, came at a time when PATA drives held tens to hundreds of gigabytes.
In 1986, the SCSI standard was published for connecting hard disks and other devices, such as tape drives and scanners.
The standard allowed several devices to work on the same bus at the same time and offered high performance, so it was used where transfer rates higher than those of IDE were needed.
Looking at its timeline, the first SCSI had a maximum transfer rate of 5 MB/s at a frequency of 5 MHz, with up to 8 devices on a single bus.
The Ultra-640 SCSI version, on the other hand, ran at 160 MHz with up to 16 devices and a maximum transfer rate of 640 MB/s, slightly higher than the roughly 600 MB/s of SATA III.
The introduction of Enhanced IDE
Coined in 1994, the term EIDE (Enhanced Integrated Drive Electronics) refers to a set of extensions to the ATA-1 standard.
Also known as Fast ATA, Fast IDE or ATA-2, EIDE offered much faster transfer rates than IDE.
While the original IDE controllers supported transfer rates of up to 8.3 MB/s, EIDE supported up to 16.6 MB/s, twice as fast.
EIDE also supported drives of up to 8.4 GB, compared with the 528 MB supported by IDE.
The introduction of the SATA interface
SATA, the successor to PATA for connecting hard disks and optical drives to the motherboard, was introduced at the start of the 2000s to replace the old wide ribbon cables.
In short, SATA is an interface that connects storage devices to the host system.
Several versions of this interface have since been released, each with more bandwidth.
The first 1 TB hard disk
In 2007, Hitachi Global Storage Technologies launched the world’s first 1 TB hard disk: the Deskstar 7K1000.
Its main features were:
- SATA or PATA interface;
- 7,200 RPM;
- 32 MB buffer (SATA) or 8 MB (PATA);
- Perpendicular recording;
- 5 platters and 10 read/write heads;
- Shock protection.
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Conclusion
Hard disks have made remarkable progress over the years, and their evolution is far from over.
As devices become more modern and feature-rich, hard disks will keep changing to keep pace.
But whatever the technology, what matters most is keeping your stored data safe, don’t you agree? And that isn’t always the case.
Whether through device failure, a fall or unsuitable conditions, you can end up losing the data stored on your hard disk.
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