The SIM cards in cellular telephones might be smaller than a postage stamp and less than a millimetre thick but that hasn't stopped South Korea's SK Telecom from cramming all the major components needed to run Google's Android OS inside one of them.
The carrier's Android SIM, a prototype of which is on show at this week's Mobile World Congress in Barcelona, includes an ARM-based processor, companion memory and 1GB of flash memory to store the OS and other data.
SK Telecom envisages such a SIM card could be used between a number of "dumb" terminals, devices that have ancillary peripherals such as a screen and keyboard but lack a processor and pre-installed OS. The SIM card uses the USB 2.0 interface to communicate with the terminal.
All of the user's applications and data are stored alongside the OS in the SIM card, so the user's desktop could be transported between devices by switching the SIM card between them. For example, a PC desktop could be switched into a cell phone for a commute.
SK Telecom said it's only a prototype at present and there are no plans to bring it to market but its development shows the level of miniaturisation and amount of hardware that can be crammed inside a cell phone SIM card.
In April the carrier, which is South Korea's largest mobile operator, will rollout a series of customised SIM cards preloaded with applications and other data. Several "smart SIM" cards are being demonstrated at Mobile World Congress. They include a financial SIM that includes an application to monitor markets, a SIM branded by a pop group that includes their music videos and a sports-themed SIM from a soccer club.
SK Telecom is also experimenting with a SIM card with built-in wireless electronic money function. The card could be used to add wireless e-payment to handsets that don't have such a feature built-in.