The first buffer in the memory hierarchy that the CPU looks for information. This cache always is onboard the processor die and running at full processor frequency. All Intel chips have 32k of L1 cache, and all new AMD chips have 128k.
Cache that is closest to the processor: typically located inside the CPU chip. Can be implemented either as a unified cache or as separate sections for instructions and data. Also referred to as primary cache or internal cache.
(L1) Also known as primary cache, L1 Cache is a small amount of high-speed memory that resides on or very close to the processor. L1 Cache supplies the processor with the most frequently requested data and instructions.