When did AMD start making clones of Intel chips? What was the first chip they cloned?
From the wikipedia article:
In February 1982, AMD signed a contract with Intel, becoming a licensed second-source manufacturer of 8086 and 8088 processors. IBM wanted to use the Intel 8088 in its IBM PC, but IBM's policy at the time was to require at least two sources for its chips. AMD later produced the Am286 under the same arrangement, but Intel canceled the agreement in 1986 and refused to convey technical details of the i386 part. AMD challenged Intel's decision to cancel the agreement and won in arbitration, but Intel disputed this decision. A long legal dispute followed, ending in 1994 when the Supreme Court of California sided with AMD. Subsequent legal disputes centered on whether AMD had legal rights to use derivatives of Intel's microcode. In the face of uncertainty, AMD was forced to develop clean room designed versions of Intel code.
The first computer my family owned, purchased in 1992, contained an AMD 386 processor.
Though not an answer, a couple minor things people may find interesting.
Intel came out with the 486, called it the i486 (for Intel obviously). They tried to trademark it, the judge threw it out. Just 26 companies could trademark the whole language (same reasoning when Zilog tried to trademark Z80). They learned they needed a name, and came out with Pentium(TM).
The licensing agreement actually helped Intel once 64 bit extensions came out. They put their bets on Itanium. AMD came out with AMD64 extensions and cleaned up in the market. Eventually Intel saw the handwriting on the wall and copied the extensions as EM64T. They could because of the original licensing agreement.
The most advanced Pentium class processor design probably was Cyrix 5x86. It bridged the gap by dividing CISC instructions into microops that were more RISC like and easier to process. The new processors now all do this, and the newest chips not only decode to microops, but they cache the microops and not the x86 instructions anymore.