A computer needs several things to run correctly. The central part is the motherboard, which connects all other parts of your computer. Next in line is the computer’s central processing unit (CPU), which takes all inputs and provides the corresponding output. CPU, in turn, needs to lay down all the information it needs to process somewhere. In modern processors, this usually happens in a memory area that handles instructions and data at the same time; this is called single instruction, multiple data (SIMD). However, some older systems used two or more separate memories for instructions and data, which slowed them down considerably. Modern computers solve this problem by using cache memory between the CPUs and main memory, but this still creates restricted access times for data when it's needed.