On Fri, 2006-03-10 at 14:19 -0800, uncutno wrote:
> Ok, last question + thank you wery much for all the help!
> 
> If the FPGA got 10k gates, it is better to have a separate RAM circuit
> since i will need maybe 32kb of ram? Or should i go for a bigger FPGA?

Hmm, well, that again depends on what you want.

External RAM is a good idea if changing the amount of ram is important,
if RAM speed isn't that important, or if sticking with a standardized
type of RAM is important (i.e. using DDR SODIMMs from the notebook
world).

OTOH using the internal RAM of the FPGA is generally much less error
prone since you just instantiate the RAM primitive and use it (vs.
bringing all the pins to top level, connecting them correctly to the
parts, and then hoping the external RAM parts don't dissapear 5 minutes
after you fab the board!). Generally using the internal memory in an
FPGA has minimal impact on both the logic capacity of the FPGA and the
speed you can run it at.

For a modest amount like 32kbits I would personally stick with the
FPGA's internal memory (Xilinx terminology is "block rams", I don't know
what Altera calls them). The EP1K50 has ~40kbits, aside from being a
slightly larger package (144-TQFP) it is basically the same as the
EP1K10 you were looking at before.

Note also the EP1K10 in the 100-TQFP package only has 66 IOs. External
memory is very good at sucking up huge amounts of IO depending on what
you choose, so even if you go with an external memory you may have to
upsize to the 144-TQFP anyways! :)

TTYL

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