Flash storage throughout the ages

Thomas Wellburn
September 20, 2016

With the announcement of SanDisks huge 1TB SD card, it really makes you think just how far flash storage has come in the past decade.

The first commercial Secure Digital (SD) card was released way back in 1999, through a joint venture by Panasonic, Toshiba and SanDisk. It replaced the older MultiMedia Card (MMC) format, which was released two years prior by SanDisk and Siemens. At only 1MB in size, you’d be lucky if it could half an MP3 or a single JPEG photograph.

The SD format was bigger and bulkier but had faster data transfer speeds, meaning in the ultimate war of formats, it was always going to win. Equally, MMC came under pressure from the music industry for lacking any strong piracy features. As such, the SD was roped in as a more secure replacement. Offering higher levels of copyright protection and faster speeds, it only took a few years for the MMC format to disappear completely.

By 2006, SD had progressed to a newer, high capacity standard. Named SDHC (for high capacity), it supported capacities up to 32GB and much faster transfer speeds, up to 25 MB/s. An inherent problem with the new standard was a lack of compatibility between older SD cards and the new HC format, so it was concluded that all future SDHC devices must also accept the older format to avoid alienating some users.

This was later replaced by an even faster standard in 2009, SDXC (eXtended Capacity), which supports cards up to 2TB in size. Announced at the Consumer Electronics Show in 2009, the first SDXC card to go on sale was made by Pretec and had 32GB internal storage. Initially released with a transfer speed of 50 MB/s, the newest version 4 standard can go as high as 156 MB/s. By 2010, capacity had doubled to 64GB and by 2011, cards with 128GB were fast becoming the norm. More recently in the past two years, we’ve seen cards with 256GB becoming more widely available and SanDisk announcing 512GB SDXC variants.

Flash storage: New standards and beyond

flash storage

A very new standard which has only come about in the last few years is Ultra High Speed (UHS) memory, which acts as an extension of the existing SD flash storage format. Built into some SD cards, you can tell by the little ‘U’ symbol in the corner and the extra row of connectors on the back. This essentially quadruples raw performance, allowing data transfer speeds up to 104 MB/s in version 1 of the format. UHS-II is the current standard and was introduced at the same time as version 4 of the SD format, offering speeds up to a blistering 312 MB/s.

SanDisks latest 1TB SDXC card is only one step away from maximizing the format, since the total supported capacity only reached 2TB. If you’ve ever wondered why memory doubles each time, it’s a surprisingly simple answer. Computer processors work in binary, which is 0’s and 1’s. This is essentially a power of two, meaning it makes sense to keep memory sizes in tune with the CPU. Once 2TB is reached, memory card manufactures will need a new format, of which there is currently not much discussion about.

Since 1TB is already a ludicrous size for an SD card anyway, it’s likely that they will focus on speed improvements, starting with the newest UHS-3 standard.

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