Schneier on Security

Clive Robinson • September 15, 2026 10:59 AM

@ Bruce, ALL,

The IEEE article says,

“The Cray-1 was built from faster, more tightly integrated circuits that could outperform Harvest’s aging transistors at nearly any task, including text processing.”

Whilst true to a certain extent, not just misses a point, but gets it wrong with,

“Harvest didn’t found a dynasty. But, in its time, it steadfastly pointed toward the future—in several directions at once.”

Little known was that many of the “Oh so Secret” ideas in Harvest actually ended up as secret “optional extras” in Cray hardware for years to come.

And some of the Harvest and Cray additions made it into Intel Chips and still are with us today.

One thing that did not make it through the ages in general computing was “Content Addressable Memory”(CAM) that was in some ways very useful for crypto and some types of high speed “lookup Table” work.

Invented by Dr Dudley Allen Buck who worked at one time for the NSA, CAM can still be found in very high end Network Devices.

Clive Robinson • September 15, 2026 8:04 PM

@ cls,

With regards,

“That’s wrong. CAM is ubiquitous in layer 2 Ethernet switches.”

Two things,

Firstly what you say does not make my statement any the less true if you pause and think for a moment.

Secondly I did not want to get down into the weeds of switches and routers, type 1 or “Binary CAM”, type 2 or “Ternary CAM”(TCAM) and the “Lulea trie” algorithm that uses a tree structure in RAM to avoid using either type of CAM hardware, thus ordinary PC hardware and similar can be utilised.

What is called Binary CAM is what tends to be used in switches, TCAM is often needed in routers.

For various reasons what was favoured for cryptanalysis work was TCAM (I’ve been told the reasons are still regarded as classified in the US but not in many other places).

You can see traces of this in what Seymour Cray designed into his computers.

One of the “not for ordinary use instructions” on the Cray was a type of “find parity” instruction that would provide the count of set bits in a word of defined size. Something that used to involve a “shift, test, increment” loop that grew with word bit length on ordinary CPUs. It’s descendant is actually quite useful in Data Comms and is used in Error Correction and similar codes.