a 'Demo-Loader' for the Elf Recreation

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Nov 5th 2022 was my first time at the Retro Computing Festival at the Centre for Computing History in Cambridge. What a brilliant event so nice to meet net-mates in person at last.
The standard of homebrewing on display was astonishing, with a huge variety of projects on show. I took my David Aitken SC/MP running Kitbug, the PICL, Southern Cross Z80 which scrolled a message for 48 hours, and the Cosmac 'Elf' Recreation.
The Elf isnt easy to demonstrate because even the simplest LED-flashing program has to be keyed in in binary using the switches, and longer programs are fraught with keying errors.
To make it easy, I made a self-contained demo-loader, which plugs onto the keypad header and downloads one of my four demo programs in turn.
It could do more, but I only have four!
The demo-loader has no extra controls, just an unmodified Nano with its inbuilt reset button.The key to this is nonvolatile variable for selecting the mode. Its probably a well-known technique but one I've not used before - it could equally be used in a servo-tester, where the reset button selects neutral, left, neutral, right in sequence, moving on every press of the reset button. Its just another trick to use for whatever purpose - the world is your lobster :)

Another idea would be instead of running its uploads in sequence, you could read the Elf toggles to make a selection. You'd have to return them all 'up' to actually load though.
Heres the Elf keypad/serial-loader video:
Cheers
Phil

[chuckbigham]

What type of "Nano" are you using?