Precisely. I started high school in 1992 and the only two IBM-PC compatibles in the computer class (the rest being CP/M machines) were an XT-8086 and an AT-80286. The XT had a very fast Turbo Pascal compiler, I don't recall the exact version but could have been 3.0. AT machine had 5.0 or something and was significantly slower although not to render it unusable. That's until someone wiped out 3.0 from the XT machine and replaced it with the same 5.0. Compile time of a simple "hello world" program raised from under 1 second to at least a minute. Rendered unusable and worst part was that 3.0 was completely gone, no floppies to re-install it. They had it solely on the hard drive (probably 20Mb or so) but now was gone.

Ok, but no IBM PCs shipped with an 8086 processor. Maybe you mean an upgraded clone, or the 286?, which was a significant leap.

Wikipedia says the first line of PCs maxed out at 256k of RAM. Except on expansion card. Not until the XT did it support 640k on board.

Also, importantly I meant 8088 above! Not easy to stay accurate after all these years, right? We were reading Petzold's Code recently and it goes on and on about the 8080, and so believe that made its way into my writing.