This invention relates to binary logic circuits, and more particularly to emitter coupled logic circuits (ECL).
A widely used dual-in-line package for logic integrated circuits is limited to fourteen or sixteen pins. As a result the number of inputs and outputs to a logic circuit used with that package are limited by the pins on the package. Thus the integrated circuit designer also is pin limited; that is, his circuit design is constrained by the number of inputs and outputs allowed by the package type selected. Often the availability of an extra input allows the inclusion of an additional logic function to be in the same package.
Moreover, two different users may require similar functions in an integrated circuit, but these functions are often different enough to prohibit a manufacturer from meeting both users' demands with the same integrated circuit due to the limitations of the package. A solution in the past has been to incorporate both functions on a single integrated circuit chip, but to change the metallization on the chip for the two different users to modify the function to satisfy the user requirements. However this solution has the undesirable effect of requiring separate device types, separate inventory, separate testing programs and separate processing steps for the two device types. It can be appreciated that a dual function input which would allow a logic circuit to perform the separate and distinct functions required by two separate users would be highly desirable.