MCA, developed by IBM, was the first bus capable of changes through software. It offers the user a slight increase in speed over the original ISA connector, and it provides the user with the option to use 16 or 32 bits. The MCA bus’s advantages where not enough to outweigh its disadvantages. Since IBM copyrighted the MCA slot technology, developers had to pay a large amount of their profits to IBM. In addition, it was incompatible with the original ISA bus. These problems contributed greatly to its shortfall. In appearance, the MCA bus looks extremely similar to the ISA bus. MCA cards are also identifiable by their tendency to have a blue handle on one or both ends. 

Shown here is a MCA expansion card.