"Turbo"

[Jim Horn]

Yes, the HP-67 could be run at roughly double speed as well by changing the capacitance of its LC clock oscillator. If you lifted one end of the stock capacitor from the circuit board and wired a second smaller value in series with it, it ran faster. By shorting the added capacitor, it ran at the original speed.

My '67 ended up with a flush mounted toggle switch that did just that as well as a momentary contact phase zero interrupt pushbutton that allowed creation of virtually any desired bit pattern in memory. Great for creating custom register data on cards to explore the then-new HP-41C: one weekend I pressed around 20,000 keystrokes doing same. Aah, the days of free time!