The wolrds leading Technology brand SONY are the only electronic consumer goods manufacturer to have stuck with their own proprietary removable memory card. Their sony Memory Stick brand, introduced in 1997, actually covers a variety of different formats that have evolved as devices have changed, getting physically smaller but demanding more storage capacity. As with other memory card formats, the cards are made with solid state memory that retains the data once it's removed from a device, so is used to backup data or transfer it to a PC. The term Memory Stick (MS) is a Sony trade mark for their memory cards and should not be confused with USB memory keys, or thumb sticks. They are often referred to as memory sticks but this is a generic term.
Sony Corporation introduced their own format as a way of tying customers into their products, and are able to do this because they are strong in a breadth of consumer product markets where a method of transferring information such as pictures, videos, music and general computer files is required. MS cards are used directly in digital cameras, camcorders, mp3 players, Playstation game consoles and Sony Ericsson mobile phones. To enable the contents to be read by PCs, USB card readers can be used, or adapters that allow a Memory Stick to mimic another memory card format. These adapters for Memory Stick to PC Card or CompactFlash (CF) conversion are more expensive than those required for some other card formats as they need a controller chip to facilitate the translation.
The table below gives a quick reference to the essentials of the different formats that have evolved. The original format was used until the 128GB limit became much of a limiting factor, despite the introduction of a double sided card (known as Memory Stick Select) so Memory Stick PRO was introduced to resolve this problem. The MS PRO format took the theoretical maximum capacity to 32GB and was also faster than the original. It was quickly followed by the Memory Stick PRO Duo, which introduced a shorter and thinner physical form factor, more compatible with the smaller devices emerging at the time. This physical size issue became more imperative with the emergence of even smaller, thinner mobile phones and led to the introduction of the Memory Stick Micro, also known as the M2, jointly developed with mass market memory manufacturer SanDisk, specifically for that purpose. The final version, again jointly developed with SanDisk, is the PRO-HG Duo, physically the same as a PRO Duo but with faster read and write times to cope with the high-speed data transfer requirements of high definition digital cameras and video recorders.