Processors

ARM is a family of RISC (Reduced Instruction Set Computer) processor architectures, originally developed by Acorn Computers in the UK starting in 1983 as the Acorn RISC Machine. Unlike Intel or AMD, ARM Holdings doesn't manufacture chips -- it licenses its architecture designs to companies like Qualcomm, Apple, and Samsung, who build their own chips around it.

BGA (Ball Grid Array) solders the chip directly to the board using an array of solder balls -- not a removable socket connection at all. It's common in laptops, ultra-compact devices, and embedded/mobile processors where board space and thinness matter more than the ability to swap the chip later.

LGA (Land Grid Array) puts the pins on the socket rather than the chip -- the processor has flat contact pads instead of pins, reducing the risk of chip damage since a bent-pin problem falls on the cheaper motherboard rather than the CPU. Intel adopted it for desktop CPUs in 2004 with Socket 775.

PGA (Pin Grid Array) puts the pins directly on the processor package, with the socket providing holes instead -- the inverse of LGA. AMD used PGA for its mainstream desktop sockets for years, including AM4, before shifting its mainstream line to LGA with AM5 in 2022.

RISC-V is a free, open-source RISC instruction set architecture developed starting in 2010 at UC Berkeley -- unlike ARM or x86, it can be implemented without paying any licensing royalty. It's currently most common in microcontrollers and embedded systems, with higher-performance implementations for mobile, desktop, and server use still in development.

x86-64 is the 64-bit extension of the x86 architecture, developed by AMD and first specified in 1999-2000 under the name AMD64, shipping in the 2003 Opteron. Intel followed with its own compatible implementation in 2004, initially branded EM64T and renamed Intel 64 in 2006.