Just in case it's any use to anyone, here's my DIY adapter for connecting the serial download circuit to a breadboard or to a real project on stripboard (or PCB for the more enterprising members). It originally came about (a) to save the cost of the jack socket and (b) because the tiny pins on the bottom of the jack socket kept popping out of the breadboard mid-download, which became frustrating. I started using JST XH connectors, which have the advantage of fitting the 0.1" spacing, are not very expensive and come with any number of pins between 2 and 6. I now use them for all of my connections. I saw a thread here a while ago about using a double row of 3-pin headers to plug securely into a breadboard. This combines that solution with a JST plug that plugs into a JST socket in a soldered project. The two halves of my adapter come apart at the JST plug/socket to allow either breadboard or permanent fixing. The labels are there so that I don't have to look at the diagram each time. The plug is connected to the stripboard with short right angle wires, and a good blob of epoxy to hold it firmly. It would be entirely possible to include the two resistors on a slightly extended piece of stripboard between the jack socket and the JST plug, but I included the resistors on the boards of my earliest projects so now I would need to redo them or have two separate adapters, one for projects with and one for projects without resistors. It's easier to keep adding the resistors. I would never have thought of using the header pins without the thread here, so I hope this provides inspiration for someone out there. The even better solution of course would be simply to use a double header socket on a soldered project and the same double row of header pins would then do both types of project. My excuse is that I didn't know about header pins when I started, so if I were to change now, I would have to redo a few early projects.