Intel x86 architecture word size

Motaz Saad

Architectures don't have word sizes, implementations do. (Or so some people will say.)

memory

Let's take the IBM 360 architecture. Most people call it a 32-bit architecture, because the general registers, defining the default integer precision, are 32 bits long.

With the Intel 8086 processor, for that reason, the word length would be 16 bits. The Intel 80386 processor, which defines the current x86 architecture, retained the 8086 instruction set, but in addition allowed instructions to be prefixed by a byte that indicated they operated on 32-bit quanbreasties.

Is it a 32-bit architecture for that reason, or a 16-bit architecture with a 32-bit extension?

There IS, however, one unambiguous number that can be given as a 'word size' for an architecture. At least for most computers I am familiar with. It gives some strange answers, though:

Intel Itanium word size: 128 bits Intel Pentium word size: 8 bits IBM 360 word size: 16 bits SDS Sigma word size: 32 bits CDC 6600 word size: 60 bits Motorola 68000 word size: 16 bits Motorola PowerPC word size: 32 bits

Before I reveal the answer,

*drum roll*

does anyone care to say just what this "word size" consists of?

I've added alt.folklore.computers to the list of groups because there are people there who might be able to see the answer...