This is minimalist computing taken to the extreme! The new "XS" platform allows an even smaller computer design. Compared to the original My4TH computer board, the new XS platform has a much more compact microcode. I reduced the width of the microcode counter from 8 bits to 4 bits, so I could remove one of the two 74HC161 counter ICs from the design. I also removed the two 74HC574 ICs used for parallel I/O and the 74HC541 tri-state driver. The new My4TH XS uses only 13.75 ICs! Why 13.75? Because...