Comment by rob74
6 hours ago
> The AMD Am29000 processor came out in 1987, also announced as the world's fastest processor (do you see a meme here?) and it could process one instruction every cycle, so indeed it was fast.
The AMD 29k - the fastest CPU you never heard of? No, seriously, I am quite interested in computer hardware, and Computer Architecture by Patterson/Hennessy was required reading during my studies, but I can't say I ever heard of this CPU architecture, which is "based on the seminal Berkeley RISC" (according to https://en.wikipedia.org/wiki/AMD_Am29000). And it seems to have been quite widely used, but not in an actual computer (except for this one)...
You might have heard of the x86 cpu the AMD K5 that competed against the Pentium?
Well that was basically an am29000 but with an x86 instruction decoder front end. The architecture was that good it was competitive 10years later.
Think of the am29000 as an incredibly influential research project that flowed into all of AMDs future CPUs in some way or another.
> Well that was basically an am29000 but with an x86 instruction decoder front end.
The K5 was based upon a 29K-family design, but it was actually an un-released superscalar project code-named "Jaguar", rather than just a 29K with an x86 decoder.
> Well that was basically an am29000 but with an x86 instruction decoder front end.
Sad. A 29K saddled with an ugly and kludgy ISA.
Wow, I wasn't aware of that either! I didn't have an AMD K5 PC, but (IIRC) a K6-III - did that still have the same underlying architecture?
No. AMD K5 did not have successors.
AMD bought the company NexGen and K6, K6-2 and K6-III were based on the NexGen design. I had been the happy owner of a K6-2, which did not have the integrated L2 cache of K6-III, but I had a friend who had bought earlier an AMD K5.
The K6 family also did not have successors, as Athlon had a very different microarchitecture, with a lot of inspiration from DEC Alpha.
The AMD K6 family of CPUs has the distinction of being one of the very few modern CPUs that are described in an entire book: "The anatomy of a high-performance microprocessor : a systems perspective" by Bruce Shriver.
I am not aware about any comparable description for any more recent CPU, because nowadays the companies have become much more secretive.
It is likely that the publication of many details about K6 was also approved because it was an architecture abandoned by AMD, as they focused on Athlon for their future (this was not yet known publicly when the book was launched, in 1998).
Yep, it wound up as the main CPU in a bunch of laser-printers, as well as Apple's 8*24GC QuickDraw accelerator card for the Macintosh, and as part of the flight-control computer on Boeing 777s, among many other embedded system designs.
It's the 'other' major processor that shipped with register windows along with SPARC and i960. Very popular in the embedded world.
This is because history gets written by the victors.