On 2025-09-30, Michael Stone <[email protected]> wrote: > On Tue, Sep 30, 2025 at 04:08:56PM -0000, Greg wrote: >> In computing, a word is any processor design's natural unit of data. A word >> is >> a fixed-sized datum handled as a unit by the instruction set or the hardware >> of >> the processor. > > It has that definition (among others), one which mapped cleanly to > historic processors, but which is much messier when dealing with modern > CPUs. E.g., amd64 mostly has 64bit instruction operands and types, but > there's also an 80 bit floating point type and with AVX-512 extensions > has 512 bit registers and can transfer data to/from memory 512 bits at a > time in a single instruction. So is the word size 512? 80? 64? > Conversely, if someone confidently says "its word size is 64", what does > that tell you/what can you do with that information? If it's a term > divorced from practical applications then it's just a historical > curiosity. If someone has to add a bunch of asterisks and explain away > functionality that doesn't cleanly fit into the model, how relevant is > the model? >
I think the key word here is *natural* (the machine's general-purpose integer registers, the ones used for addresses and integer arithmetic, not the specialized, vector register widths).
