I just realised it. I had had a small linux partition for a few months, but on the 6th of August I added this to the todo list for the Sinclair Spectrum emulator JPP :
These will not get done. Ever. I'm done with JPP. (I wrote JPP on MSDOS, using the wonderful TopSpeed Modula 2, but MSDOS was in my past.) Having written that, I reformatted my hard drive to 100% linux and started ferrying floppies home from university. Several days later, 20 years ago today, I had a working all-linux system. Since then, my home directory has been on linux, except for two forays into freebsd.
20 years. Wow.