 When the system grew beyond 32 TCUs, an additional 6 SSUs were added.Two of these SSUs connected to TCU32-TCU63 in a manner directly analogous to the first two SSUs.Two connected the inputs from TCU0-TCU31 to the output of TCU32-TCU63, while the final two connected the outputs of TCU32-TCU63 to the input of TCU0-TCU31.