To facilitate developing new circuits for my 65816 system, I have designed an extension for my bus, leveraging the ISA physical connection on my motherboard. The extension consists of a pair of PCBs -- one that plugs into the motherboard and one that hosts an ISA connector. A pair of ribbon cables then connects the two. This allows me to work on add-in cards that are lying flat on my workbench, allowing easier access to probe and modify.
With shorter ribbon cables:
To further support development of new circuits, I have designed an add-in card that hosts a pair of breadboards. The card provides easy access to bus signals and power. This card and the extension above are going to come in handy!