Solid State Drives (SSD) – A Brief History

Most modern computers come equipped with an SSD (Solid State Drive) as a replacement, or compliment, to the more commonly used HDD (Hard Disk Drive).

To explain what an SSD is all about we first need to delve into the inner workings of a normal HDD. An HDD works similar to how an old vinyl record player works, but instead of a record it has spinning disks coated with an electromagnetic material. Where the record player has a groove and a needle to interpret the data, the HDD has magnetic charges that represent either a 1 or a 0 (Binary), which an arm reads to puzzle together the data stored. This is one of the disadvantages of a normal HDD; with its moving parts it’s subject to sensitivity from physical shocks and movement.

An SSD on the other hand works in a similar fashion to RAM (Random Access Memory), or flash memory. The SSD stores data on chips instead of disks, which both makes it faster and more resistant to shocks – and as an added bonus it runs silently. As with the HDD, it is a non-volatile memory, which means it retains its data even if it loses power.

The origin of the SSD started in the 1950s with the development of two similar technologies: magnetic core memory and charged capacitor read-only storage (CCROS). However, with the introduction of drum storage units these technologies were abandoned as they were too expensive.

It took all until the 1970s for SSD technology to be considered again as it was implemented as semiconductor memory for early supercomputers from IBM, Amdahl and Cray. However, due to their relatively high price, SSDs were used sparingly.

In 1978, Texas Memory Systems introduced a 16-kilobyte RAM solid-state drive to be used by oil companies for seismic data acquisition. The following year, StorageTek developed the first RAM solid-state drive.

In 1989, the Psion MC 400 Mobile Computer included four slots for removable storage in the form of flash-based "solid-state disk" cards.

In 1991 SanDisk Corporation created a 20 MB solid-state drive (SSD), which sold for $1,000.

In 1995, M-Systems introduced flash-based solid-state drives. They had the advantage of not requiring batteries to maintain the data in the memory (required by the prior volatile memory systems), but were not as fast as the DRAM-based solutions. This could be considered the birth of the modern SSD, and the technology was soon taken up by the military and aerospace industry for mission-critical tasks. As a piece of trivia, SSDs work in zero gravity, due to their not having any moving parts. As such, they were used in space missions by NASA.

Various improvements were made from 1995 onwards, and now SSDs are a solid (pun intended) alternative to everyday HDDs, even though the price per megabyte is still on the expensive side when compared to the old mechanical drives.