Dual D.C. Sense Amplifier 4551B 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
The board is surrounded by an aluminum frame and blue plastic 22 pin male connector. One side of the board is covered with various active and passive components. There are two inspection stamps in the top corner.