Through a friend-of-a-friend, I did actually manage to get a copy of the source code to CTSS, the cray time sharing system, on microfiche from Lawrence Livermore National Lab, and I even had it digitized (but not OCR'd), but it's written in a language called COMPASS i've never found a compiler for.
From what I've heard, part of it relates to volume. If someone asks to declassify a single page document, it is pretty easy to evaluate it and decide whether it can be released or not. Presented with thousands of pages of old source code, it is an immense undertaking. Added to that, people don't understand the old source code any more, and worry that there might be something lurking hidden in there that should not be released, but they might not notice it due to not understanding it.
I hope at least they never destroy any of this old stuff, and maybe one day (even if only decades or centuries from now) the US government will decide that enough time has gone past that it no longer could pose any risk.
The Cray-1 was really distinctive in so many ways.
Sounds like a fitting end for the project.
"It is a mix of FORTRAN source code and Cray Assembly Language (CAL), and looks like it supports the Cray 1, Cray X-MP, and Cray Y-MP machines, and possibly a SPARC machine."
Note that the special sauce behind this is the same as the special sauce behind fast inverse square root. The integer bitwise components of a floating point number permit a really good approximation of the log base 2 of it. And once you have the log base 2 of a number simple arithmetic does interesting operations.
log2(x^-.5) = -.5 \* log2(x)
log2(x^-1) = -log2(x)
The same trick can be used to calculate any constant power over the range [-1,1]. -.5 is the most famous for whatever reason, probably because of the "what the fuck?" comment in the open source quake code.
I'm not entirely sure why this knowledge was known at Cray, then lost, and had to be rediscovered at SGI or whatever. And I'm not entirely convinced it ever was lost. But if it was lost, I imagine it had something to do with replacing engineers whose bread and butter was done on a sliderule (which is inherently built on the premise of manipulating logs of numbers) with engineers who always had a pocket calculator.
> The same trick can be used to calculate any constant power over
> the range [-1,1]. -.5 is the most famous for whatever reason,
> probably because of the "what the fuck?" comment in the open.
> source quake code.
Note that this bit is rather outdated. :) The FPGA on an entry-level development board (like a Xilinx Artix-7 35T) is comparable in size -- as well as much faster! -- and you can go even bigger without stretching your budget too much.
If you're willing to get a little adventurous, in fact, you can get an FPGA that's over ten times the size for under $200:
For some products, such as their Zynq 7000 dev boards, you can also get a cheap time-limited copy of Xilinx SDSoC which allows easier device driver development to the programmable logic side:
(on the other hand, this is the first time I heard about the cray replica)
"It didn't get traction originally" was referring to https://news.ycombinator.com/item?id=20660889, not to the links above.
Haven't you read laundry files? You could accidentally summon an alien horror from another dimension.
That said, my Linux laptop with a 1070 GPU and CUDA does about seven trillion float operations a second. For modern times, the old mainframes don’t seem useful.
Fun to imagine what the computer might look like 45 years from now - everyone will have a gigabits quantum computer in their pocket?
NO, I want an 11 Pro with them three cameras!!
(But I am waiting for someone to emulate a Cray on a phone.)