Thread: Test Board
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  #37  
Old 04-21-2008, 11:24 PM
Grant Stockly Grant Stockly is offline
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Join Date: Jan 2005
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An 8bit AVR at 20MHz is too slow for a 2MHz 8080.

The AVR is fast enough, but it would require a CPLD.

I interfaced a SCENIX directly to the ISA bus once. It required external address decoding. I think I was running at either 1 or 8MHz bus speed, but with like 30 wait states, so I'm not sure what the "final" speed was.

The INSTANT the ISA would access the scenix, the scenix would ask for wait states. It was tough. The scenix was running at 50MHz. Probably not as efficient though.

A CPLD and an AVR is MORE than fast enough. Its not that the AVR wasn't fast enough to process the data, but that its not fast enough to read the address, figure out what goes where, return data, etc. Too much to think about in the 1us allowed.
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