To scan double you have to buffer an entire line (maybe closer to 2)
You write to the line buffer once at 15KHz and you read it out twice at 31KHz. The time taken to fill the buffer is the same time it takes to empty it.
It would take 2 minutes to do in VHDL with even the smallest FPGA.
However you need to remember that at the 23-pin connector the signals are ANALOG they are not TTL.
If you intend to make something that connects to the Amiga video connector you will have to digitise it (A2D) and after scandoubling you will have to convert to Analog (D2A) which you could do with a simple R2R ladder.
If you have some idea about what chips you are going to use... post the datasheets here.
What is 20 NZD in real money? Hmm.. about 8 quid... that means that your scandoubler is going to cost (to make) at least £25 (70NZD).
Last edited by alexh; 16 October 2006 at 22:30.