. The 1x series, at 1.8, is for SXs and the 2x series, at 2.3, is for DXs and up. If it's a 486DX it must not be a coprocessor problem. I mean, like I say, it isn't usually, but it would be if you tried to install 2.3 on a 386SX. It just aborts the boot process, exiting with an error message. But other distros may just abort silently, leaving you wondering.
Mind you, I don't think BasicLinux is all that great - it uses busybox, which is a bunch of symlinks to an executable that kind of emulates most of what would be your /bin directory and a lot of switches are missing. But it gets a 102 meg 25 MHz 486SX running, so I can't really complain, either. (Maybe I should say it *is* great, given the constraints, which suck.) Plus, you can download some old Slackpacks, usually without much trouble.
Oh, and I should say that Basic *is* a floppy distro but you can download bas2hd.zip and transfer it to your hard drive so that it's a real distro. My memory's getting fuzzy. I think it needs DOS to get started. If you don't have an old DOS laying around, try FreeDOS. That's a DOS-compatible open source system. Then, after BL's on the hard drive, just delete FreeDOS if you want.
Or maybe somebody else knows something simpler and better.