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Altera_Forum's avatar
Altera_Forum
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14 years ago

MAX V LE RAM - how much per LE ?

Seems Altera really like to hide the simplest information.

The MAX V data says

the quartus ii memory compiler can configure the unused les as le ram.

max v devices support the following memory types:

■ fifo synchronous r/w

■ fifo asynchronous r/w

■ 1 port sram

■ 2 port sram

■ 3 port sram

■ shift registers

and points to the MAX_V_ug_ram_rom.pdf, but that merely says 'yes'.

Then MAX V Device Selection Guide says

  1. Unused LEs can be converted to memory. The total number of available LE RAM bits depends on the memory mode, depth, and width configurations of the instantiated memory.

but NOWHERE can I find how much RAM per LE ?

I hope the info is not 'omitted' because the answer is an abysmal 'one RAM BIT per LE' ?

Can anyone point to an answer to this ? is it 1, or 8, or 16 or ? RAM Bits/LE

I just need a simple,small table RAM - the order of 4 address bits to 12 bits wide.

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    --- Quote Start ---

    Can anyone point to an answer to this ? is it 1, or 8, or 16 or ? RAM Bits/LE

    --- Quote End ---

    It's < 1. You have one memory bit per LE, but usually need additional LE's for address decoding and an output MUX. Very small RAMs like the said 12x4 should work.

    Why don't you simply try in Quartus?
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    --- Quote Start ---

    It's < 1. You have one memory bit per LE, but usually need additional LE's for address decoding and an output MUX. Very small RAMs like the said 12x4 should work.

    Why don't you simply try in Quartus?

    --- Quote End ---

    Thanks.

    I do not have MAX V capable Quartus installed, and was wanting to avoid the time/hassle, if the MAX V really had poor RAM support - as you confirmed.

    Even with their higher base-price, this will likely make the MachXO2 a better fit. (Lattice just need more QFN package options)