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Altera_Forum's avatar
Altera_Forum
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14 years ago

device size disproportional number of user IO pins

Hi, I have a question related to the number of user I/O for a the Cyclone IV E family for example, ....but I believe this issue may be common to other devices as well... Looking at the tab...
Altera_Forum's avatar
Altera_Forum
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14 years ago

Yes ...I mean within the same package but not only,... this phenomenon also happens for all device sizes including packages....

... in particular of interest to me (and I believe if I can explain this maybe I can find an explication for the rest of devices too) which also is the most peculiar case ...is why the device EP4CE22 (22,320 LE which is a "medium" size device) has a smaller number of I/O than the most smaller device EP4CE6 (6,272 LE) (pag. 1-3 table 1-1) ?... it makes no sense :( ...

Furthermore ....I mean isn't this discordant with "Rent's rule" :confused: ?

..the thing is that in Xilinx this is not happening....in Xilinx it is always the same no mater what device you choose: more logic = more I/O = more $...and it does agree with Rent's rule... more logic blocks => more IO

... something is wrong...but I just can't figure out what....?.