[rockrr]

Define “working” LoL.

I have an Osborne C/PM that dates to 1983 and a Compaq luggable that dates to 1984.

[Poser]

I have an Apple II with a CP/M card installed.

[Paul R.]

Define “working” LoL.

Successfully boots to the OS and can run, oh, maybe a 3rd party text editor, execute batch files, can execute something in Fortran...

You've got me beat on oldest, though. My old DOS 3 machine was still working several years ago, but, I think my brother snagged it for, well, I don't remember...