NCSA creates Sony PlayStation2 cluster (2003)
ncsa30.ncsa.illinois.edu
ncsa30.ncsa.illinois.edu
Though it is basically just a Linux system, nothing special about it aside from the instruction set. When i ported a DOS game i made some time ago to it[3] all i did was install Debian and Free Pascal on a MIPS QEMU system, make sure it compiles with SDL and package the binary in the package format its launcher uses (OPK, which IIRC is essentially a squashfs image).
[0] https://en.wikipedia.org/wiki/GCW_Zero
[1] https://en.wikipedia.org/wiki/Ingenic_Semiconductor
I'm sure there are a few asterisks to this, but the WRT54G (the iconic Linksys blue and black wifi router) has a MIPS 32-bit CPU that's ~4x as fast as the PSX and ~1/2x as fast as the PS2.
32MB of RAM that the PS2 had would be really tight for modern kernels.
https://openwrt.org/supported_devices/432_warning
But CPU-wise I don't foresee that ~300MHz MIPS would be any sort of major roadblock.
When WRT54G was available kernel was 2.2 or 2.4
I did have some fun with that kit, despite the typical monitor issues, even with a sanctioned distribution.
US Air Force connects 1,760 PlayStation 3's to build supercomputer https://phys.org/news/2010-12-air-playstation-3s-supercomput...
It turns out that in order to do that, you sort of had to reinvent how software works. While that was possible, it was hard enough that only very few developers tried to tackle it (SSI clusters, mostly). So somebody else figured out that rather than do all that really hard work that would take years to get right, you could just start your program 100 times on 100 different computers and send each a random request, with all of them using one database and a lot of caching. Poof: "web-scale" is born, and around the same time, a bookseller started providing APIs and renting hardware.
It is 20 years later and we are still using the same architecture.
Nice article though.