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Altera_Forum
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16 years ago

memory usage by DCFIFO in cyclone III

I'm trying to get an understanding of the memory usage by the DCFIFO MegaWizard function in a cyclone III application. For example, in my application I'm looking at a FIFO that is 18 bits wide ...
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Altera_Forum
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16 years ago

See Table 4-1 of the following:

http://www.altera.com/literature/hb/cyc3/cyc3_ciii51004.pdf

I would assume the M9Ks are set up in the 8192 x 1 configuration. (8192deep x 1wide) Thus, for 18 wide, it would take 18 M9Ks.

To pack into 16 M9Ks, it would have to stack 16 of the 512 x 18 configuration.

The 8192x1 configuration is probably faster and uses less logic then the 512x18 configuration. In 9.0, there is a checkbox called Reduce RAM usage, may be in other versions also. Checking this box yields a 18wide x 8k deep fifo that uses 16 M9Ks. Unchecked, it uses 18 M9ks.