Although Compaq had become successful by being 100 percent IBM-compatible, it decided to continue with the original AT bus—which it renamed ISA—instead of licensing IBM's MCA. Prior to developing EISA Compaq had invested significant resources into reverse engineering MCA, but its executives correctly calculated that the $80 billion already spent by corporations on IBM-compatible technology would make it difficult for even IBM to force manufacturers to adopt the new MCA design. Instead of cloning MCA, Compaq formed an alliance with Hewlett Packard and seven other major manufacturers, known collectively as the "Gang of Nine", to develop EISA.