If you mean amd64 it's the 64 bit extension of the x86 instruction set. It's just named after AMD because they were the ones introducing it while Intel was instead working on the arguably failed brand new 64 bit-only Itanium architecture. In the end they "went back" and picked up amd64 too that's why multiple names exist: x64, x86_64, amd64.
And there were/are some differences between AMD and Intel 64-bit x86 once you get into the details (and indeed between various extensions on a given microarchitecture). x86_64 (or x86-64), ugly as it is, is probably the best way to refer to specifically 64-bit x86 at a non-vendor-specific level. Just x86 works for a lot of purposes too.
AMD had their own non-x86 instruction set once upon a time. I remember using it in the mid-90s in some embedded thing it worked, but as a developer once there is a compiler all instruction sets are hidden so I can't comment.
The article says it got designed in to a bunch of laser printers, but not which ones.
There were a bunch of RISC designs floating around then. The ones still relatively familiar are those that were being used as workstation CPUs -- SPARC, MIPS, POWER/PowerPC, DEC Alpha. But there were also the 29k, the Motorola 88000, and Intel i860. Probably others I'm not remembering.