The CPU needs two types of memory: random access memory (RAM) and storage memory. RAM chips hold the data and instruction set to be dealt with by the CPU. Before a CPU can do its job, data are quickly loaded into RAM—and wiped away from the RAM when the work is done. RAM, until a few years ago routinely measured in “megabytes” (the equivalent of typing a single letter of the alphabet one million times) is now stated in “gigabytes” (roughly one billion letters). Microsoft's Windows 7 operating system claims to function with as little as gigabyte of RAM (Microsoft, 2009). Few PCs ship with less than 1 gigabyte of RAM; standard consumer-aimed computers ship with at least 2 gigabytes.