Byte sizes (was Re: 2.8M 3.5' floppy (was: three and a quarter loppy?)
mouse at Rodents.Montreal.QC.CA
Mon Mar 14 10:46:54 CST 2005
>> A byte is the smallest INDIVIDUALLY addressable unit of data on a
Well, it sounds reasonable, but probably isn't the most useful, as it
would mean that, for example, the PDP-8 had 12-bit bytes.
> The PDP-10 is an excellent example of when this isn't true.
> The smallest addressable unit is a word, which is 36 bits.
> A byte is, as noted, anything between 0 and 36 bits. Bytes are
> stored in a word, as many as can be fitted. To access bytes on a
> PDP-10, you have a byte pointer, which consist of a word address, and
> a bit pointer, and byte size.
That sounds a whole lot like a hardware-supported way of addressing an
object of an arbitrary size in bits. And that would mean that bytes of
any size *are* individually addressible.
Or have I misunderstood?
> The fact that people today seem to believe that byte addressable is
> the only possible thing, along with a byte being 8 bits, is plain and
> simply because they haven't seen any other.
There even are relatively modern machines which don't fit it very well.
Some DSPs, for example, have 32 bits as their smallest directly
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