What is a word and how many bytes are in it?

[Binamra]

What is a Word? Half-word? How many bytes are there in one word?

[Anuj Dhawan]

In computing, "word" is a term for the natural unit of data used by a particular processor design. The mainframe "was" originally a half-word, full-word and double-word centric system.

Said that - A full-word is four bytes in length, a double-word is eight bytes long and a half-word is two bytes long.

Hope this helps.

[Sandy]

So the memory will always "swap" only words and not "bits" of information?

[Robert Sample]

If you are talking about memory swaps (such as paging to / from auxiliary storage), the unit used is a page. And a page is 4096 bytes (4KB or 1024 words).

[Binamra]

Thanks Robert (and Sandy). I look at other post of yours Robert - that also helps.

[Robert Sample]

An update to my previous answer: z/OS now supports large frames for handling memory objects in the 64-bit address space (above the bar). Large frames are referenced in 1 megabyte (1,048,576 bytes) increments and are NOT paged with the older 4K pages.