ASICS 101 for dunces?

[ThrillHou]

 
So, in trying to learn more about ASICS and their impact on the world, I went to the asic wiki page, and got immediately lost in technical info.

I get that ASICS do one thing really well. In this context, that thing is solve SHA-256 hashes. Some say Litecoin is “immune” or “resistant” to Asics. Why? What is different about scrypt which makes it so? And ultimately, can you speculate on the downstream impact of this in terms of coins and their prices as a result of mining impact?

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[grue]

hint: use google.
https://en.wikipedia.org/wiki/Scrypt

The large memory requirements of scrypt come from a large vector of pseudorandom bit strings that are generated as part of the algorithm. Once the vector is generated, the elements of it are accessed in a pseudo-random order, and combined to produce the derived key. A straightforward implementation would need to keep the entire vector in random access memory so that it can be accessed as needed.

Because the elements of the vector are generated algorithmically, each element could be generated on the fly as needed, only storing one element in memory at a time and therefore cutting the memory requirements significantly. However, the generation of each element is intended to be computationally expensive, and the elements are expected to be accessed many times throughout the execution of the function. Thus there is a significant trade off in speed in order to get rid of the large memory requirements.

Such a trade off often exists in computer algorithms: you can increase speed at the cost of using more memory, or decrease memory requirements at the cost of performing more operations and taking longer. The idea behind scrypt is to deliberately make this trade off costly in either direction. Thus an attacker could use an implementation that doesn't require many resources (and can therefore be massively parallelized with limited expense) but runs very slowly, or they could use an implementation that runs more quickly but has very large memory requirements and is therefore more expensive to parallelize.

[suryc]

To put it more simply, scrypt requires the chip to have access to a lot of direct memory, so the existing Asics could not be used for that.
It would be technically be possible to build one for mining Scrypt, but the best you would end up with is something very similar to a GPU (just without the video outputs). Since GPUs are already mass-produced, it seems unlikely that a Scrypt Asic could be cost-competitive anytime soon.

Also, this topic has already been discussed at length on this forum and there are already numerous threads already on this topic.
Maybe do a quick search next time before you start a new thread. Just a few of the existing threads:

https://bitcointalk.org/index.php?topic=117488.0
https://bitcointalk.org/index.php?topic=116987.0
https://bitcointalk.org/index.php?topic=231199.0
https://bitcointalk.org/index.php?topic=213872.0
https://bitcointalk.org/index.php?topic=231185.0
https://bitcointalk.org/index.php?topic=187900.0
https://bitcointalk.org/index.php?topic=103085.0