The following CPU only has 4th x86 generation features:
Right answer: AMD Am5x86
Yes, the AMD Am5x86 only had 4th x86 generation features, unlike the Cyrix 5x86 or other 5x86s. It is just an Am486 with 4x internal clock multiplier.
The following compatible math coprocessor had to be used before the introduction of the Intel 80387 FPU
Right answer: Intel 80287
Before the 80387 was introduced, people with 386 based systems had to install a 80287/80287XL math coprocessor which was much slower than the later 387.
386 class motherboards could run CPUs with 4th x86 generation features. Which one is NOT an upgrade?
Right answer: Intel i486 OverDrive
The i486 OverDrive was designed to speed up SX 486 CPUs and to upgrade x1 multiplier CPUs to x2 or more. Both RapidCad and 486SL/DLC enabled having 4th x86 generation features on 386 class motherboards.
The Intel 80486 combines
Right answer: Level 1 cache, FPU
Yes, the Intel 80486 was the first CPU to have integrated first level cache (therefore also an integrated cache controller) and the first Intel CPU to have a Floating Point Unit (FPU) integrated. The FPU is used to speed up the performance of math calculations. The i486 SX represents the only exception: It doesn't have a FPU.
Not sure where to go?