When it is your (White's) turn to move, the chess board will gently pulse to show the influence of the various pieces. in the left image below, you can see waves over the squares around the king and (very lightly) over the squares where the pawns might capture. When the machine (Black) is thinking, a network of curves is overlaid on the board; see image at right. The curves show potential moves--often several turns in the future--considered by the computer. Orange curves are moves by black; green curves are ones by white. The brighter curves are thought by the program to be better for white.

I'd forgotten all about this - not my favorite for actual gameplay, but fascinating to watch..
Link: Thinking Machine 4: About
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