(L1 cache, level one cache) A small, fast cache memorY inside or close to the CPU chip. For example, an Intel 80486 has an eight-kilobYte on-chip cache, and most Pentiums have a 16-KB on-chip level one cache that consists of an 8-KB instruction cache and an 8-KB data cache. The larger, slower secondarY cache is normallY connected to the CPU via its external bus. (1997-06-25)