Hi Countzero,
I wonder if the DE2 Tobias used is 5v tolerant ?
DE2 (and the DE2/70) boards have clamp diodes on the GPIO connectors which give some measure of protection against 5V.
The more inputs you have which are driving over 3.3V however, will tend to raise the core voltage on the FPGA.
Not normally a problem for Address/data lines which are actively driven by buffer chips.
Not so for Active low signals on the AMIGA bus, which will typically have pull-up resitors to 5V. More of these you have, FPGA core voltage will drift higher.
Over about 4V tends to permanently damage the the FPGA.
Plenty of references on Altera site/Cyclone datasheets to absolute maximum ratings.
DE1 board has no clamp diodes. If you were to try hooking the DE1 GPIO connectors straight to the Amiga bus
like:
http://www.a1k.org/forum/attachment.php?attachmentid=22915&d=1264849250I supect you would fry it very quickly....
Red
