Yeah... the thing I didn't mention about my family's old 386sx/16 was that it was similar to what you describe. That machine was an ALR PowerFlex, which came o

Yeah... the thing I didn't mention about my family's old 386sx/16 was that it was similar to what you describe. That machine was an ALR PowerFlex, which came out of the box as a 286/12. However, it also had a special CPU upgrade slot that allowed installation of higher end CPUs on daughterboards. Our machine had a 386sx/16 on a daughterboard, but ALR let you install CPU's as fast as a 486DX/25 into what was fundamentally a 286 box. If you didn't mind your state of the art 486 being limited to 5MB of 16-bit memory, it wasn't a bad choice. (This machine started my general thinking that upgradable hardware is overrated as a long term plan to keep equipment viable.) Earlier than that, Cheetah made something reminiscent of this called the Adapter/386. It was a cheap way to install a 386 into a 286 machine. This gave you the ability to run 80386 specific software, but actually wound up making the machine a little slower. My guess is that they didn't sell many, and the primary takers were developers that wanted to get a cheap way to develop 80386-specific software without buying a new machine. https://books.google.com/books?id=jE2OlZ9PkrkC&pg=PA251&lpg=PA251&dq=cheetah+adapter/386&source=bl&ots=8jWAiU2Cvv&sig=mWubwLfUfedWO6qfhKyHLyDeLcc&hl=en&sa=X&ved=0ahUKEwiWwOWoi6fUAhUmxoMKHRXRCesQ6AEIMzAG#v=onepage&q=cheetah%20adapter%2F386&f=false https://books.google.com/books?id=jE2OlZ9PkrkC&pg=PA251&lpg=...