To the left we have the top and bottom board layouts for the ‘universal’ Z80 processor card. Far from being really universal, it is somewhat limiting in it’s depicted state. Note that although the layout includes a 2K RAM, it is a ‘skinny DIP’ variety. If using a 6116 or larger variant, remember to allow for more room on the board. The two IDC type headers need not be on the board either, which will free up some space for perhaps the system clock circuit or oscillator module? Remember that the 74xx139 is a dual decoder so the unused half can be used for expanding the I/O if desired.
Of course the family can be changed to all HC devices in place of the specified LS.
Note that the parallel lines on the underside layout are the suggested positioning for the wiring combs.