The Inquirer timeline shows the 1989 Intel 80486 as the first to have an on-chip cache.
The Xerox microprocessor (called a “Low Cost Controller” for political reasons) was the first to have on-chip RAM. First silicon 5/28/1976...
When the 80486 first came out we were installing it in our clones in Fremont, CA and they came back full of bugs from our customers- It was a big loser at first. Intel used the clone mom and pop operations as beta testers for the 80486.