CDC 6600 emulation - was Re: How do they make Verilog code for unknown ICs?
Guy Sotomayor Jr
ggs at shiresoft.com
Wed Jun 22 18:54:04 CDT 2016
> On Jun 21, 2016, at 11:07 PM, dwight <dkelvey at hotmail.com> wrote:
> Well Ben
> I'll tell you a secret. I work for one of those two companies.
> Processors are designed from such code, simulated and then
> synthesized to silicon gates. I don't think that is too much of a
> How the architecture is done is very much a secret. I can tell you that it is more complicated than one person can completely understand. It is a team effort with many people working from a general description of what each part does and how it should interact. Some work only on arrays while others work on floating point alu's and so on.
Having worked for both of those companies, I can also state the the number of people doing the high level design/architecture of
these chips is measured in the 100’s. Most of the time the architects (I was one) write documentation in excruciating detail as to how
something is to work (and why) to be handed off to the design team(s) to actually implement. In many ways it would’ve just been
easier/faster to write “code” but it’s harder for others to really know the why’s and wherefore’s and make sure that everything is worked
out properly before hand (on one new chip we literally spent *months* working out all of the details for the various reset and power
management flows…and that was just the docs describing how it should be done…no implementation).
> Each processor generation shares only a little with previous designs. To try to describe to someone outside how one of todays processor worked inside would require a book for each generation. Some parts are the same while other are vastly different.
If the book were several 1000 pages. ;-)
> It is interesting that I just read an article about the Chinese creating a faster supper computer. I suspect that many might think they did it with RISK design while most US made machines were stuck in CISC machines.
> I don't have the real inside scoop but I can tell you what I think. Processors made today are general purpose. Floating point is a side function and not where the most emphasis is placed. I suspect that the Chinese designed the processors they used specifically to do floating point and were not the reuse of general purpose processors. The RISK/CISC is really not even relevant in todays processors since the main limiting factor is memory access bandwidth and effective use of caches. The instruction set used is only to deal with older software.
The issue is that (much like many of the earlier supercomputers) is that they are vector processors. Today’s supercomputers have a
(large) number of general purpose cores (ie POWER, x86) but they are there to manage the real work horses which are based on graphics chips. It turns out that modern graphics chips have enormous FP capabilities. For example, NVIDIA’s newest/baddest GPU
can do 10.6TFLOPS of single precision FP (using 3584 processors on the die). Now multiply by 100’s of GPUs that are put into modern super computers.
Are they general purpose, no…they require specialized programming to perform the computations. But the HPC (high performance
computing) guys will do what it takes (and have for decades) to get the most out of the HW.
TTFN - Guy
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