In this video I show you how an Attiny85 is programmed through an Arduino Uno and then I show you the ProtoShield that I made into an ISP Programmer for easy programming the Attiny85 when the shield is stacked onto the Arduino Uno.
Here's the promised links to a great article explaining it all :
Wire up an Arduino to use as an ISP (programmer) for an ATtiny85
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http://highlowtech.org/?p=1706
Programming an Attiny85 through that prepared Arduino (working as an ISP)
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http://highlowtech.org/?p=1695