The video below shows how to connect another Arduino to do the programming. You could also use any dedicated AVR programmer you happen to have.

The impetus for this build was to replace a particular calculator, a well-used TI Programmer, that’s useful for working with 6502 assembly.

If you’re a programmer with a knack for making things — like Simon Boak — you custom build a replacement. This is the SB116, an 8-bit programmer’s calculator powered by an Arduino Nano.