Why is the pinout being increased from 68 to 72 pins, what do the added 4 pins do? Can I make a board layout to accomodate either socket to prevent having 2 revisions?

Tim Rohaly

Starting in June, 2000, Dallas Semiconductor will be shipping TINI Boards on a 72 pin SIMM, instead of the 68 pin SIMM they had been using.

This change is being made simply because 72 pins is a much more common form factor. This affects availability and cost of the sockets. The extra four pins are not connected.

The pinout of the 72 pin part is the same as the 68 pin part, with the addition of two extra non-connected pins on either end. It was designed that way so you can make a board layout which will accept either the 68 pin socket or 72 pin socket.