What Is Level 1 Cache (L1 Cache)?

The L1 cache is the little brother of the CPU. It's the first stop for information, and it's on board, so there's no need to wait around while you get what you need. The L1 cache is also sometimes called the internal cache or system cache because it's part of your processor and not a separate chip like other types of memory. The L1 cache is also used to store microprocessor data that the processor has recently accessed, so it's often referred to as a primary cache. The size of your L1 cache depends on which type of processor you have: some processors have larger caches than others, and some have multiple levels of caching. The L1 cache is built into the chip and has a zero-wait-state interface, making it the most expensive cache among the CPU caches. It is used to store data accessed by the processor recently, critical files that need to be executed immediately, and it is the first cache to be accessed and processed when the processor performs a computer instruction. The L1 cache stores copies of instructions and data the processor require during processing. It also holds copies of frequently-used data items in the main memory so that they can be accessed more quickly than if they were read from the main memory. Modern microprocessors utilize an L1 cache split into two parts: one for holding program data and the other for holding the microprocessor's instructions. On the other hand, some older microprocessors make use of the undivided L1 cache to store both program data and microprocessor instructions. These days, most of us are familiar with the concept of an L1 cache (or "Level 1" cache). It's a small amount of high-speed memory inside your computer that your processor can access for instructions or data. In some processors, though—particularly older ones—the L1 cache was not divided into two parts: It was one big pool of memory where both program data and processor instructions were kept.