located y switch card 36 y the z and t signals from most nodes go to a different mid plane and thus typically travel through electrical cables or optical fibers the signals could go onto cables at the node card or at an i o driver card 42 as illustrated in fig4 fig5 illustrates a compute rack 50 which includes four compute mid planes 40 such as illustrated in fig4 each compute rack contains 1024 compute nodes the cable or fiber connections between mid planes simplifies construction of such a rack no inter connection is provided between the compute mid planes other than by the z and t i o driver cards 42 and switch cards 36 as shown in the embodiment of fig4 smaller or larger compute racks with a lesser or greater number of mid planes are possible in alternative embodiments fig6 illustrates the cabling for the embodiment using in rack switch cards 36 z 36 t for the z and t dimensions as shown in fig4 each compute mid plane has 256 nodes therefore 256 z dimension ports from compute nodes a z switch card 36 z has 16 switch chips each chip has 16 network ports for a total of 256 ports from switch chips within the mid plane the 256 compute nodes already have their x y dimension ports connected in a 16 u00d7 16 2 dimensional switch network therefore all of the 256 z dimension ports on one mid plane need to be connected to the ports from 15 other mid planes via the corresponding z switch cards to form a complete z dimension.