On Mon, 14 Mar 2005 11:52:06 -0800 (PST)
"Eric Smith" <eric at brouhaha.com> wrote:
der Mouse replied to my description of PDP-10 byte
addressing (0-36
bits) and someone else's claim that a byte is the smallest addressable
unit of storage:
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.
Any size from 0 to 36 bits.
The problem with the "smallest addressable unit" definitition is that
it would mean that the byte size of a PDP-10 is *only* zero bits,
because that's the smallest. (Or one bit, if you can define it in a
way to rule out the zero bits case.)
Also, the MC68000 has bit-manipulation instructions that can address
individual bits, but it is not considered to have one-bit bytes.
Lots of embedded controllers, including some of the 4-bit ones that I've
programmed professionally (8 bit byte ??!!??) have bit manipulation
instructions.
This is one of those discussion threads where the stuff people bring up
is more interesting than the actual issue of 'the size of the byte.'
Eric