Building computers from discrete components is a fairly common hobby project, but it used to be the only way to build a computer until integrated circuits came on the scene. If you’re living in the modern times, however, you can get a computer like this running easily enough, but if you want to dive deep into high performance you’ll need to understand how those components work on a fundamental level.
[Tim] and [Yann] have been working on replicating circuitry found in the CDC6600, the first Cray supercomputer built in the 1960s. Part of what made this computer remarkable was its insane (for the time) clock speed of 10 MHz. This was achieved by using bipolar junction transistors (BJTs) that were capable of switching much more quickly than typical transistors, and by making sure that the support circuitry of resistors and capacitors were tuned to get everything working as efficiently as possible.
The duo found that not only are the BJTs used in the original Cray supercomputer long out of production, but the successors to those transistors are also out of production. Luckily they were able to find one that meets their needs, but it doesn’t seem like there is much demand for a BJT with these characteristics anymore.
[Tim] also posted an interesting discussion about some other methods of speeding up circuitry like this, namely by using reach-through capacitors and Baker clamps. It’s worth a read in its own right, but if you want to see some highlights be sure to check out this 16-bit computer built from individual transistors.
[Ken Shirriff] recently shared some pictures and a writeup from his visit to the Large Scale Systems Museum, a remarkable private collection of mainframes and other computers from the 1970s to the 1990s. Housed in a town outside Pittsburgh, it contains a huge variety of specimens including IBM mainframes and desk-sized minicomputers, enormous disk and tape storage systems, and multiple 90s-era Cray supercomputers. It doesn’t stop there, either. Everything through the minicomputer revolution leading to personal home computers is present, and there are even several Heathkit HERO robot kits from the 80s. (By the way, we once saw a HERO retrofitted with wireless and the ability to run Python.)
Something really special is that many of the vintage systems are in working order, providing insight into how these units performed and acted. The museum is a private collection and is open only by appointment but they encourage interested parties not to be shy. If a trip to the museum isn’t for you, [Ken] has some additional photos from his visit here for you to check out.
It wasn’t that long ago when hard drives that boasted a terabyte of capacity were novel. But impressive though the tera- prefix is, beyond that is peta and even further is exa — as in petabyte and exabyte. A common i7 CPU currently clocks in at about 60 gigaflops (floating point operations per second). Respectable, but today’s supercomputers routinely turn in sustained rates in the petaflop range, with some even faster. The Department of Energy announced they were turning to Cray to provide three exascale computers — that is, computers that can reach an exaflop or more. The latest of these, El Capitan, is slated to reach 1.5 exaFLOPS and will reside at Lawrence Livermore National Laboratories.
The $600 million price tag for El Capitan seems pretty reasonable for a supercomputer. After all, a Cray I could only do 160 megaflops and cost nearly $8 million in 1977, or about $33 million in today’s money. So about 20 times the cost gets them over 9,000 times the compute power.
Somewhere in the recesses of my memory there lives a small photograph, from one of the many magazines that fed my young interests in science and electronics – it was probably Popular Science. In my mind I see a man standing before a large machine. The man looks awkward; he clearly didn’t want to pose for the magazine photographer. The machine behind him was an amazing computer, its insides a riot of wires all of the same color; the accompanying text told me each piece was cut to a precise length so that signals could be synchronized to arrive at their destinations at exactly the right time.
My young mind was agog that a machine could be so precisely timed that a few centimeters could make a difference to a signal propagating at the speed of light. As a result, I never forgot the name of the man in the photo – Seymour Cray, the creator of the supercomputer. The machine was his iconic Cray-1, the fastest scientific computer in the world for years, which would go on to design nuclear weapons, model crashes to make cars safer, and help predict the weather.
Very few people get to have their name attached so firmly to a product, let alone have it become a registered trademark. The name Cray became synonymous with performance computing, but Seymour Cray contributed so much more to the computing industry than just the company that bears his name that it’s worth taking a look at his life, and how his machines created the future.
Sometimes it is hard to remember just how far computers have come in the last three or four decades. An old NASA video (see below) has been restored with better sound and video recently that shows what passed for a giant computer in 1986. The Cray 2 runs at 250 MHz and had two gigabytes of memory (256 megabytes of million 64-bit words).
Despite the breathless praise, history hasn’t been kind to the Cray 2. Based on ECL, it had 4 processors and –in theory — could reach 1,900 megaFLOPs/second (a FLOP is a floating point operation). However, practical problems made it difficult to get to that theoretical maximum.
The name Cray, as in [Seymour Cray] is synonymous with supercomputing. If you hurry, you can bid on a Cray J90/J916 on eBay. You might want to think about where to put it though. It is mounted on a trailer, requires 480V, and the shipping is $3,000!
First introduced in 1994, the J90 was an “entry level” machine. This particular machine supported up to 16 CPUs (each CPU was actually two chips) running at a blazing 100 MHz. The memory system was more impressive, achieving 48 GB/s.
The Cray T90 computer was much faster (and more expensive) but none of these computers had the performance of a typical PC’s graphics card these days. Even your phone may have more raw computing power, depending on how you choose to measure. Don’t fear, though. Cray Research still makes supercomputers that can eat your phone for lunch.
Still, at the time, this was big iron. The I/O system used SPARC processors that would have been entire workstations in that era. The eBay listing says it might need a little work — we weren’t clear if the seller meant in general or just the cooling system, but you can assume this is a fixer-upper. Apparently, the Retro-Computing Society of Rhode Island restored a similar beast so it can be done.
[Chris Fenton] needs your help. After constructing a 1/10th scale, cycle accurate Cray-1 supercomputer and finding a disk with Cray software on it, he’s ready to start loading the OS. There’s a small problem, though: no one knows how to boot the thing.
[Chris] posted a disk image for a Cray-1/X-MP with the help of the people at archive.org. Now he needs your help – if you think you can reverse engineer the file system, [Chris] will pay handsomely with a miniature model of a Cray printed on his MakerBot. In any case, it seems like a fun challenge.
From our quick glance at the disk image with a HEX editor, it looks like [Chris] has something special on his hands. We see a few references to “Cray memory and registers,” as well as “IOP-0 Kernel, Version 4.2.2” in the header along with a few dates referencing July of 1989. This is consistent with the history of the source disk pack. If you think you’ve got what it takes to reverse engineer the file system of a Cray-1, this is your chance.