Has anyone seen that before?
I especially liked the pbrush predescessor.

I really didn't think they had optical mice back then. But then it had more drawbacks such as only working on a certain mouse pad at a certain angle.
And as the for PC Paint, its not really a predecessor of Paintbrush, it actually seems much more like MacPaint than anything, I mean it even has Mac style menu bar and everything.

I own one of those (mouse systems mouse). It needs a special mouse pad and a power cord. Kinda awesome, if I had the mouse pad or power cord.

Same here. Pretty useless without the special pad, but I've got an Atari power block so I may have to figure out what angle the pad reflects at to build my own pad.

This is apparently an early optical mouse from Mouse Systems.

Mouse Systems was among the first producers of mice for the PC, along with Microsoft and Logitech, especially, I think, as graphical user interfaces started coming into common use. I find it very interesting that someone made a video regarding this early optical mouse.

Remember that from the 1950s to the 1970s, having anything like a mouse on a computer was basically non-existant (with one notable exception to the Xerox Alto in 1973), but with the first functionally complete and widely successful microcomputers, and also with the first commercially available graphical user interfaces, the mouse went from being what people would have mostly only read about in news reports and seen on TV shows, to being almost taken for granted as being part of most computers, but as the original uploader of this video pointed out, it wasn't until the end of the 1990s and the beginning of the 2000s that optical mice came into common use.

I remember reading that it was possible to make a makeshift mouse pad by printing a fine grid on an overhead transparency. I wish I remembered where I read that.

Sometimes I wish my Goodwill was that awesome. It's quite fascinating to see that optical mice were made in the 80s..I really didn't think such a thing existed for that time, blew my mind.

nice mouses ! nice.
Those are very picky about surface but I don't think this is Your problem.. it should give some respond

The college club I was a part of actually happened to have one of these in storage since they've been around since the 80s. Pretty neat, requires the special mousepad as mentioned which when held up to a light looks like a rainbow grid (much like you see from light reflecting off the bottom of a cd). However that aside, I wouldn't think anyone would use one these days--the limitations are more trouble then its worth and more versatile optical mice are a dime a dozen now. Definitely a nice addition to anyone's collection however.