Excalibur Mirage Marble
Excalibur Mirage Marble 2 20 x 20

The Excalibur Mirage is a robot chess computer which moves its pieces by means of a plotter mechanism under a press sensory chessboard. It is a well establish method of providing an interesting and entertaining chess opponent. The human player makes their move by pressing the from and to squares, moving their chesspiece accordingly, and the chess computer makes its reply by moving a magnetic pickup under the chessboard which ‘collects’ its piece and drops it off where required.

This mechanism was first seen in the Milton Bradley Grandmaster, Milton and Phantom robots released in 1983. Please see my webpage on the Milton Bradley Phantom (link). This robot type was further developed in 1988-1991 with the Fidelity Phantom, Chesster Phantom and Chesster Phantom Eyeball (link) and then continued by Excalibur with the Mirage in 1996 and in 2007 with the Phantom Force. So you could say there have been four generations of plotter mechanism robots.

The Excalibur versions are the least successful because of failures in the mechanisms caused by component economies and faulty engineering. Most Milton Bradleys are still working well after 30+ years. But most Mirages have either stopped working altogether, many with the notorious ‘Stall’ error, or exhibit errors which have to be corrected by resetting and in some cases avoiding using the ‘setup’ function. For pictures of the Mirage mechanism and electronics please see Berger’s excellent website (link).

Excalibur Mirages are not rare. However the vast majority of Mirages that were manufactured were black (see bottom picture). The number of marble coloured Mirages is very limited which makes the Excalibur Mirage Marble rare, especially outside of the USA.

The Mirage has the same chess program as the well known Excalibur Grandmaster. It was authored by Ron Nelson working with Grandmaster and chess program expert Larry Kaufman, who was responsible for the relative strength of the program (1780 Elo), which was beyond Nelson’s capabilities on this hardware.


Excalibur Mirage Marble 3 10 x 10 Excalibur Mirage Marble 1 15 x 15
Excalibur Mirage Marble 4 20 x 20
free counters