Does anybody know SHOP-DOS 3.0?

[Trash-Eighty]

In a recently ended Ebay auction a Model 4 was sold and the auction's photos contained a photo of the computer's screen with a DOS called 'SHOP-DOS 3.0'.
Does anybody know this DOS?

 

[Tibs]

From looking at the pictures that looks like something internal to Radio Shack. Its a guess, but I'd expect thats what it is.

 

[Trash-Eighty]

Listed again.

-Rainer