More thoughts on building a Z-80 (64bit!!!)

< It's a right pain to do complex digital circuitry like this. Great for < RF amplifiers, etc, but not so easy to run data buses across the board. < Although you _can_ make striplines using strips of copperclad stuck down < to the groundplane if you have to. for bussed logic is can work. The trick I used was 2sided clad board with one side sliced to produce 8 narrow strips as a bus with it's own groundplane. It was elevated over the chips with some screws (also passed the ground) and then wires picked off the needed signals. this approach was used to hook a 8049 MCU to a DDS (digital synth) that was used to drive a PLL. The core of a DDS is a (this case) 24bit parallel adder and 24 bit accumulator plus a 24bit constant register. A lot of parallel bussed signals. It was all clocked at 16.777216(2^24)mhz. A ram card would be harder but I've done one (dram!) that was fairly small (1Mx8 using 256kx1 dips) and one off. busing is a pain only in that it's a lot of repetitive wiring. But being visible it was easy to see signal progression. The results worked well and lacked the ringing that sometimes plagues boards of two sided design. Allison