Hi, I want a ROM in FPGA which is 85 bits wide, is it possible to have one? Thanks
- posted
18 years ago
Hi, I want a ROM in FPGA which is 85 bits wide, is it possible to have one? Thanks
It depends. If you want 16-address depth, you can use 85 LUTs. With Xilinx 18K BlockRAMs, you can get 256x72 bits wide in one BlockRAM. For more, you need two BlockRAMs in parallel. Peter Alfke, Xilinx (from home)
Hi,
Yes. In Altera's devices, you just use the "lpm_rom" megafunction described in
For example, if you want to make a 96-bit wide by 32-bit deep ROM, the software might map it into three memory blocks, each 32-bits wide by 32-bits deep.
For very shallow ROMs, you might be better off mapping to logic -- a 4-LUT is just a 16-bit deep by 1-bit wide ROM after all. I don't know the best way to do this (LPM_ROM only targets RAMs, I believe), but please ask if you are interested and I'll ask around to find out.
Regards,
Paul Leventis Altera Corp.
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