A phrase used in the
electronics world to refer to a component that is not wholly identical to another but is capable of acting as a plug in replacement. Using components that have pin compatible brethren is a
big win since you can avoid
single sourcing and may have the option to buy a
faster/cheaper/better version in the future.
Often used metaphorically to describe something that is a sufficient substitute. Ex: "
7-Up is
pin compatible with
Sprite."