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deleting logic increases macrocells?

Niko3
New Contributor I
629 Views

Hi,

I have a very curious effect:

The design of my project is a schematic for an EPM3064ATC100. After compilation 51 macrocells from 64 available ones are used. When I remove an AND with 4 inputs and a NAND with 2 inputs 64 macrocells are used - an increase of 13 macrocells!

What happened?

I'd like to know if this is normal?

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ShengN_Intel
Employee
527 Views

Hi,


This is possible behavior. The original 51 macrocells likely benefited from logic optimization which AND (4 inputs) and NAND (2 inputs) could have been part of a wider combinational logic structure, allowing the fitter to place more logic in fewer macrocells.

When you removed those gates, the fitter had to restructure the logic, which could have increased the number of macrocells


Thanks,

Regards,

Sheng


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Niko3
New Contributor I
623 Views

Sorry, I changed a little bit more:

I additionally replaced an output by an input.

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ShengN_Intel
Employee
528 Views

Hi,


This is possible behavior. The original 51 macrocells likely benefited from logic optimization which AND (4 inputs) and NAND (2 inputs) could have been part of a wider combinational logic structure, allowing the fitter to place more logic in fewer macrocells.

When you removed those gates, the fitter had to restructure the logic, which could have increased the number of macrocells


Thanks,

Regards,

Sheng


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