Wow! Vintage stuff.
Whenever I see CP/M, I always end up thinking of poor old Gary Kildall and how he was robbed.
He never really recovered. Sad story.
Dr Dos (from his company) was also really good, but Microsoft arranged it so Windows wouldn't run on it.
WordStar, I remember, could be (ahem) easily copied from the computer it was running on, but WordPerfect 5.1 had an installation process.
I have box sets of MultiUser Dos and OS/2 2.0. Both nobbled by Microsoft.