I’ve finally got around to replacing my mini breadboard and bunch of dupont cables with a proper ISP breakout board. Its got a ZIF slot to make it easy to insert/remove the chips, and a couple of DIP switches the switch the location of the reset and GND pins between 8-pin ATtiny85’s and 28-pin ATmega328p’s. Just connect a 6-pin USBASP and “make ispload”.
Building it was a bit of a disaster – first I’d soldered all the wires before realising the veroboard is a horizontal type not vertical (or vice versa) and then I forgot my USBASP 10-to-6-pin adaptor had female headers on it, so I had to desolder the female headers I had put on my board and replace with male pins.
Here’s the finished item on veroboard:
And here’s the two breadboard designs I merged into one – you can see the slightly different pinout of the ICSP pins between the two chip sizes, which is annoying: