I just joined because I saw that you had this Apple II forum.
I'm one of those many people from decades ago that used to work on them.
Then I was a member of a BBS called "The PigSty" (where pigfont came from) and worked at Roland US where I also did some Apple II programming for them in my spare time. (I was a fulltime repair tech.)
My first Apple was an Apple II+ with 48K. 1979 or so, I think.
It changed configurations many times, having Sider hard drives, a Dtack68000 board, Gibson Lite pen (I was an early user) and many other bizarre peripherals, some home-made.
I still have some cards and most are shown on my small Apple II page at my website below:
I also recently started playing around with an old Mountain Computer A/D, D/A board and did this small video of what I came up with after a few hours of work:
Fwiw, I also have an Alpha Syntauri 5 octave keyboard I want to sell.
No Mountain music cards or anything else for it, but oh well.
Also some broken Sider drives and controllers lying around I can't use.
Anyway, just wanted to say hi.