Can AL3101 access external RAM?

[SeanCostello]

Hi all:

I was researching Keith Barr algorithms on the net, and found descriptions of the Alesis Ineko. Apparently this box used the AL3101, and also did reverbs. So, did it also include an AL3201? Or can the AL3101 access external RAM for delay memory?

If the AL3101 has off-chip memory access that is easy to use, it might be a better chip for reverbs than the AL3201, since it has a lot more possible instructions per cycle. Of course, if the memory access slows things down, then it wouldn't be a good option. Nothing more annoying than burning cycles on "wait for DMA to be completed"...

Sean Costello

[SeanCostello]

I did some searching of the Wavefront Semiconductor forums, and found someone else who asked the same question. Apprarently the AL3101 does not have provisions for external memory access. Does this mean that the Ineko used an AL3201 chip as well as an AL3101?

Sean Costello

[puretube]

http://www.diystompboxes.com/smfforum/index.php?topic=12010.msg74459#msg74459
http://www.diystompboxes.com/smfforum/index.php?topic=12109.msg88387
http://www.diystompboxes.com/smfforum/index.php?topic=15742.msg88381
http://www.diystompboxes.com/smfforum/index.php?topic=42626.msg310142#msg310142

maybe above links can help...

[SeanCostello]

They sure do. Thanks!

From what I can tell, the AL3201 is well designed for a particular type of reverb (allpass loop or "allpass ring"), a few different chorus and flanger algorithms, pretty basic overlap-add pitch shifting, and that's about it. It doesn't have the general purpose RAM, or enough cycles, to do much else. Randomized granulators, for example, seem like they could not be easily implemented, and there is not enough memory to calculate feedback delay networks with large matrices.

The AL3101 has far more cycles, and more general purpose RAM, but not enough delay memory to do reverbs or other longer delay algorithms.

It seems to me that the Alesis chips should be viewed as ASICs, as opposed to general purpose DSP chips. They are optimized for doing certain algorithms, and can perform them very well, but there are many algorithms out there that cannot be implemented on the Alesis chips at all.

Sean Costello