Intel® Quartus® Prime Software
Intel® Quartus® Prime Design Software, Design Entry, Synthesis, Simulation, Verification, Timing Analysis, System Design (Platform Designer, formerly Qsys)
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Generating small rom & ram for Cyclone 3

Altera_Forum
Honored Contributor II
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MegaFunction wizard doesn't seem to allow using Logic Cells for small 

roms & rams in Cyclone 3 as it allows in Cyclone 2. I don't want to 

use a M9K for a small memory block. Anyway to get around this silly 

limitation ? Am I missing something ?  

 

TIA 

 

Jim
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Altera_Forum
Honored Contributor II
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Hi,  

Using Quartus II 9.0SP2, the megawizard allows one to select LEs for RAMs but not ROMs. This seems to apply to all supported device families. Weird, I must say. 

 

Suggestions: 

a) hope for the best, ie, set it to "AUTO" and let the tools balance registers vs M9Ks 

b) do not use the ROM megafunction, use just plain HDL for your ROMs.
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Altera_Forum
Honored Contributor II
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On second thought, I think I just made sense on what's going on. 

 

With RAM/ROM megafunctions, Quartus allows one to change MIF files and the quickly update the programming files without recompiling the entire design. 

However, this is only feasible when using dedicated memory blocks. 

Thus, the following restrictions are observed: 

a) ROM megafunctions (which have to have a MIF file) must use dedicated memory blocks 

b) RAM megafunctions that force the usage of LEs do not support MIF files 

 

So, you need to go with "b)" for any small ROMs and initialized RAMs
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