Read Write Hold and Deselect 4520 D system building block
Digital Equipment Corporation (DEC)
Printed on the solder side at the insertion end
Stamped into the face of the aluminum frame
Stamped into the side of the aluminum frame
overall: 1/2 in x 4 1/2 in x 7 in
On one side of the board is half covered in various components. The board is surrounded by an aluminum frame blue plastic 22 pin male connector. "READ WRITE HOLD AND DESELECT 4520 D" is printed on the solder side at there insertion end above the grid lettered A-Z.