General Electric Speedtronic Mark VIeS IS200TBCIS2C is a Discrete Input Terminal Board and itâs designed as a terminal board for the Mark VI system. This is a very lengthy circuit board with a number of electrical components, including two terminal blocks for holding a collection of terminals. Each of these terminal blocks has 48 silver metal terminals or twenty-four terminals. They are designated TB1 and TB2 and have a number inscribed in white writing on them. This board also has five solid red capacitors positioned between the small, totally spherical terminal blocks. Additional components have been put in multiple parallel rows of four components each in the middle of the board.