The Holidays are coming and if you’re buying someone a new digital camera listen up: please…please do not forget the SD Card. I know from experience, and it is frustrating to get this shiny new toy and then not be able to use it because there is no SD card. So for your own sake, don’t do that.
SD Cards 101
SD Logo
When we think of modern day, common use digital cameras, whether we are using them for photography or video production, the cameras are synonymous with the memory cards that the cameras store their images to. These compact pieces of technology have really been a revolutionary device, allowing us to take hundreds of photos or hours of video and then seamlessly move them to our computers or laptops. So the obvious question is: How does an SD Card work? In a simple explanation, SD or Secure Digital cards is a form of portable or ‘bridge’ storage device that uses flash memory to retain its data. Very popular in digital cameras but also cell phones and portable music players.
So what is it?
Size of Flash Memory
So we know that we have to stick an SD Card into our cameras in order to store pictures, but there is much more to them than that. Very similar to ‘USB Drives’, SD Cards are have the same very simple function: store data. The roots of an SD Card can be found with floppy disk from the late 90’s but
“This modern alternative has several improvements over the old forms of memory storage. The main one is the amount of data they can hold. While it is possible to get a Secure Digital card which stores only as much data as a floppy disk, these days you’re more likely to find the 2-8 GB variety. That’s the equivalent of around 8,000 floppy disks in something only a little larger than a stamp” (David Tube, ezinearticles.com).
SD Dimensions
Among the size difference, the most advantageous aspect of the SD Card is the durability of the technology. Traditional hard drives and other data storage devices like optical discs contain physically moving parts. This becomes a hindrance if you’re looking for storage that is portable and will be undergoing travel and exposure to the elements because those moving parts inside become vulnerable and have a high rate of breaking and consequently will lead to loss data.
“In contrast to traditional hard drives, SD cards also contain no moving parts, so they are significantly more resilient to accidental bumps and falls. This has contributed to their use in MP3 players, which are often subject to shock”(eHow, How Does an SD Card Work?).
The familiar devices that we associate with SD cards require that the data storage device allow for frequent and specific changes to the data. An example is your cell phone or portable music player. The information on those devices is constantly being changed and must have storage that can be accessed in very specific ways. This is another reason that SD cards have become so popular. The other factor that makes SD Cards and Flash memory so popular is that they do not require a power source to access your data. HowStuffWorks.com explains this and gives an example
“You may think that your car radio has flash memory, since you’re able to program the presets and the radio remembers them. But it’s actually using flash RAM. The difference is that flash RAM has to have some power to maintain its contents, while flash memory will maintain its data without any external source of power. Even though you’ve turned the power off, the car radio is pulling a tiny amount of current to preserve the data in the flash RAM. That is why the radio will lose its presets if your car battery dies or the wires are disconnected” (Jeff Tyson, HowStuffWorks.com)
How does is work?
SD Diagram
So how exactly does it work? Well, as was mentioned earlier, SD cards are a form of Flash Memory and store the data digitally. That doesn’t answer the question on how it actually works though. What is Flash Memory, right? I will go ahead and apologize, it it is about to get very technical, but HowStuffWorks.com has the best expliexplination
“Flash memory is a type of EEPROM chip, which stands for Electronically Erasable Programmable Read Only Memory. It has a grid of columns and rows with a cell that has two transistors at each intersection. The two transistors are separated from each other by a thin oxide layer. One of the transistors is known as a floating gate, and the other one is the control gate. The floating gate’s only link to the row, or wordline, is through the control gate. As long as this link is in place, the cell has a value of 1. To change the value to a 0 requires a curious process called tunneling. Tunneling is used to alter the placement of electrons in the floating gate” (HowStuffWorks.com)
In short, SD cards function as holding cells for bytes of data that is transported through the Control Gate and Floating Gate. Through a series of electronic circuits the data is transported either to the SD card or off of the SD card.
What is next?
There is no doubt that SD cards or at least Flash Memory are vital to almost everyone these days. The SD Association makes the claim that
“SD technology is the de-facto industry standard for mobile phones, digital cameras, MP3 music players, personal computers, printers, car navigation systems, electronic books, and other consumer electronic devices. SD technology is used in some 400 products across dozens of product categories and in more than 8,000 models” (SD Association, SD Technology).
What does the future hold for SD cards, can we foresee a day when there are 100 gigabyte SD cards with a write speed that is comparable to hard drives? Sure, I see that day coming very soon. More importantly though is how many different applications they will have. How many different pieces of technology already use an SD card? There is our cell phones, mp3 players and digital cameras. But also some more nontraditional things like cars. Audi, for example, has a line of vehicles that accepts SD cards that can store music and pictures that displays on their media interface. Imagine that from the time we wake up an SD card is more like an ID card. We could use it to house critical information that Paramedic’s could access in case of an emergency situations or have. The future is endless for SD cards and over the next few blogs I hope to expand on how their small part plays a vital role in the overall realm of not only in digital cinema, but in ever increasing technological lives.
DSLR Cinematics Blog 
Good information – a easy read. Would have liked to read a solid tease at the end.