I found it very difficult to find references to it online. There is a reference in the "Hackers" book by Steven Levy to Sierra On-Line having one (he uses the name "Form Master"), and former Sierra employees have mentioned it as well but with the two words run together as FormMaster. As I couldn't find much more, I'm not sure which form of spelling is correct.

https://www.google.co.uk/books/edition/Hackers/JwKHDwAAQBAJ?...

There is a photograph in a September 1983 issue of a Japanese magazine called "LOGiN" of one of Sierra On-Line's disk copying machines but the article doesn't mention it by name. I wonder if it is the FormMaster/Form Master machine.

https://archive.org/details/login-september-1983/LOGiN%20-%2...

As an aside, that September 1983 magazine is the earliest clear reference to the development of King's Quest that I could find. It isn't mentioned by name but it is obvious that it is King's Quest that is being referred to.

Thank you for the links! I kind of expected a machine with 10+ floppy slots (: I think I just wasn't really aware of the year this machine was produced.

This video that Ken Williams put on Youtube a year or so back has got a short bit showing someone using the machine in the Sierra On-Line office:

https://www.youtube.com/watch?v=oY_JbTYXVjg

It is at about 1:47 into the video. It is the same machine shown in that LOGiN magazine article. This one appears to only support the 5 1/4 inch floppies, since I think the 3 1/2 inch disks weren't around at the time, so they must have got a newer machine later on.

Ken's title for the video claims it was from 1983, but from my research, I think that a September 1982 date is more likely. The whole thing is an amazing video actually. Well worth watching. Incredible that it actually survived and is now preserved on Youtube.

Good catch! Thank you.