This is an old post, preserved for reference.
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[Update: Please see the new version which supports multiple fonts and 'medium resolution' graphics]
I know I only updated the Arduino 80x25 text tv / video output library yesterday, but whilst I was doing that, a further improvement occurred to me. The original interface was 8 bit parallel with two handshaking lines. This is about as fast as it is going to get, but tricky if you don't have 10 I/O lines available. The recent update was to add 4 bit mode. This effectively halved the speed by splitting the data into two nibbles, but reduced the required I/O pins to 6 (4 bits plus two handshaking). Well. I thought I could take that a step further. It is again fewer pins, now only two are required, but it is slower than the parallel version.
Grant Searle's original with 4bit or 8bit parallel interface, and the new I2C only version.
here. This zip file includes the source and hex files and source for both versions of the video processor, and an updated version of the library which supports I2C mode.
It is possible to use the Video Processor in I2C mode without the library, just using the wire library.
// your code
If you go for just the Wire library, you will need to deal with the issues of the 32 byte Wire buffer and small packets.