Came across this article from Radio Electronics November 1977, that's 30yrs ago this month, amazing. Full article on the site including schematic!
I'll have to do a software version for my Dragonfly kit. Lets see 6 pushbuttons = 6 users, DS1302 RTCC on board yep. http://www.decodesystems.com/oebc.html **broken link removed** **broken link removed**