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Old 18 January 2015, 17:23   #1452
Join Date: Jun 2010
Location: out in the wild
Posts: 1,254
Originally Posted by dJOS View Post
Be nice if we had the option tho.

Edit: e.g. Via acaTune to select an FPU compatibility mode that was stable and fast.
That compatibility mode would mean extra states in the memory controller state machine, which is next to impossible with the amount of logic already fitted in these small 9572 CPLDs.

The problematic thing with FPU as additional load on the data bus is burst. If you switch off burst, it's likely that the board is stable. However, since I can't test it with the specific FPU that you have chosen (there's a bunch of different masks), I can't guarantee it.

I need satisfied customers, because I need you guys to recommend my products to each other. If I promised anything that I can't keep, you'd complain (and you'd be right about it!). I've tried to make the ACA1233-40 as "hackable" as possible, for example by keeping the holes for the PGA FPU open and adding a space for a canned oscillator, so you have a choice of sync clocking (just close the solder-jumper) or async with the canned oscillator (that's an either-or choice, you should not close the jumper and install a canned oscillator at the same time).

Who knows, maybe such a hacked unit is even stable with your choice of FPU? The select/autodetect logic is all there. Just don't hold me responsible if it doesn't work. It's a hack, and you are responsible for it.

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