evaluating ressources saving between differents families

Hi,

in the Stratix2 Handbook, there is a table where the ALMs and the Equivalent LEs are shown. Between the two values there is a constant factor of 2.5. This value can be used as reference value.

Of course the exact calculation depends on the design. E.g. large multiplexers can be realized in a better way in a Stratix II because of the possibilities to use the LUT as Six-Input LUT.

On the other side, in Stratix devices each LE keeps a register. In Stratix II devices the number of equivalent LEs is not the number of registers. (Each ALM keeps two Registers)

So each device/vendor has different strengths and it depends on the design how much ressources are needed. (e. g. the DSP blocks from Altera and Xilinx are different and can make timing problems when porting designs from one vendor to the other one)