Great job.. thanks for sharing..
In 1989 I worked for a company called something Dynamics, in East New York ?
I was asked to solve a problem to stop criminals from stealing the money of a Mafia company.. of course the didn't tell me they were Mafia! But in fact they were. Without going into details I ordered OrCAD PCB Layout and Schematic Capture software. More than $500 at that time, and started climbing the learning curve. It was so intuitive and easy to use.. the PCB could automatically execute up to 16 layers but I only wanted two. I used Zilog's Z-80 CPU. I loved that animal specially for the separate data and address pins and the few instruction set (only 70 basic instructions).
I used EPROM programmer and punched the program in hexa-decimal. To branch to a subroutine you must calculate destination address manually using one's and two's complement.. but I didn't care about the hassle because I was still young and had enough energy. Now all this is history and we are using Arduino and B4R so we only concentrate on the software.
Please pardon any typo