3 ms·
> (“a word is the natural unit of data used by a particular processor design”) Apparently on x86 the word size is 16 bits, even though the registers are 64 bits
by 908B64B197 4y ago
> (“a word is the natural unit of data used by a particular processor design”) Apparently on x86 the word size is 16 bits, even though the registers are 64 bits.
That's true for the the original x86 instruction set. IA-32 has 32 bit word size and x86-64 has... you guessed it 64.
16 and 32 bit registers are still retained for compatibility reasons (just look at the instruction set!).
- loeg 4y agoSome x86 categorizations would call those dwords and qwords respectively.
- stefan_ 4y agoIt's extra fun because not only are the registers retained, they were only extended. So you can use their 16 and 32 bit names to refer to smaller sized parts of them.
- tom_ 4y agoWords aeem to be always 16 bits for the x86 and derivatives - see the data types section of the software developer manual.
- dragonwriter 4y agoI think "word" as a datatype evolved from its original and more general computing meaning of "the natural unit of data used by a processor design" (the thing we talk about with an "x-bit processor") to "16 bits" during the period of 16-bit dominance and the explosion of computing that was happening around it. Essentially, enough stuff got written assume=ing that "word" was 16 bits (and double word, quad word, etc., had their obvious relationship) that even though the term had not previously been fixed, it would break the world to let it change, even as processors with larger word sizes (in the "natural unit of data" sense) became available, then popular, then dominant.