What Does External Cache Mean?
An external cache is any cache memory that is not built into a CPU chip. External cache is designed to provide high speed data storage and processing services to the computer processor, its primary/native cache and the main memory.
External cache is also known as secondary cache.
Techopedia Explains External Cache
The development of caches is a key event in the history of computing. The system is designed to ensure that the next bit of data a CPU will need is ready in the cache when it is needed.