Ahh you wind the wayback machine way back.
This is the true story you have not heard elsewhere.
386SX vs 386DX
These where completely different die with the SX having a 16bit external bus and DX having a 32bit external bus
Internally they were nearly identical with no internal FPU.
None had an internal cache.
All 486 with the exception of the 486SX had and internal FPU. All had internal cache which was the big performance boost.
Very early 486SX had the FPU disabled but it was removed soon after intro. It was the only difference between SX-DX.
All this SX-DX nonsense was done as AMD had captured 60% of the 386 market and Intel wanted it all back by moving to 486 in a comparable price point.
During all this time, Intel was pouring tones of money into what would become “Pentium” and they just wanted to hang on till it came out.
When it was late, they came up with the DX4 as a stop gap.
It wasn’t called DX3 because DX4 sounded better.
Again all of the 486 naming issues were mostly marketing decisions designed to hang on till Pentium arrived.
Getting the first Pentium out the door was much harder than was reported.
All of this is old news and reported publicly but since you asked I thought I’d give you the history.
486 project was kind of fun.
Pentium was really really tough.
Thanks for the history lesson! I always suspected the 386SX was built as a kind of “transition” chip that let manufacturers continue to use available 16-bit components until everyone else got caught up to 32 bit.