In art and archaeology, in sculpture as well as in painting, a register is a vertical level in a work that consists of several levels, especially where the levels are clearly separated by lines; modern comic books typically use similar conventions. It is thus comparable to a row, or a line in modern texts.
Processor registers are normally at the top of the memory hierarchy, and provide the fastest way to access data. The term normally refers only to the group of registers that are directly encoded as part of an instruction, as defined by the instruction set. However, modern high-performance CPUs often have duplicates of these "architectural registers" in order to improve performance via register renaming, allowing parallel and speculative execution. Modern x86 design acquired these techniques around 1995 with the releases of Pentium Pro, Cyrix 6x86, Nx586, and AMD K5.