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Nios2 core usage of memory blocs M4K x M9K

Honored Contributor II

I was playing with a cheap development kit based on the Cyclone-II which did not suffice to fit a specific design. 

More precisely, it was required 30 M4K memory blocs, whereas the chip on the dev kit contains only 26 M4K memory blocs.  


I found another cheap kit, now based on the Cyclone-III, which apparently would meet my needs, due it has 56 memory blocs. 

However, at its datasheet it is mentioned that the memory bloc is of the type M9K , not an M4K. 


My question is:  



  1. What is the equivalence between both blocs ? 


  2. Would the system resource usage of the previous design fitted at this new chip, to be at the ratio of 1:1 ?  

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2 Replies
Honored Contributor II

4K < 9K so you are okay.

Honored Contributor II

1. M9K has 9000 bits of memory versus M4K of 4000 bits of memory. Representing about 2x more in memory capacity 

2. Quartus looks at the memory size per RAM instance, ie depth + width instantiated and hook up X number of memory blocks together. I would aspect about 2:1 ratio. 


Example, previously you have a system with a RAM of size 15kBytes (30 * 4000bits). So now you use 13 of them on Cyclone III 15kBytes * 8 / 9000 bits.