Is the built-in processor cache in the processor a technical necessity or an economic reason?

Question

Iron

By economic reason, I mean not the ability to replace the processor cache with a larger one. You have to buy a new processor, and this is sales, that is, to arrive.
It used to be good there was no money, you use percents without a cache, the money appeared, the cache was bought in addition.

Answer 1

Umm ... And what is there to think about? We drive into Google and read the materiel:
https://www.google.ru/search?q=cache+in+cpu&gw...

Answer 2

Purely technically, it is very expensive to organize a cache external to the processor chip.

Answer 3

The type of memory used in the cache is static memory. This is a very precious memory. She is expensive because it is technically difficult to make her huge - too much marriage.
Когда это такое было????
Математический сопроцессор можно было отдельно поставить.
А кэш - нет.
Только заменой процессора (старый выкидываешь).
Это и сейчас можно так делать.