Actually the terminology is much more ambiguous than that. Register
size, address size, bus size within CPU, bus size to memory, bus size to
peripherals, could all be different bit widths, and physical hardware
register sizes don't have to match the register sizes of the hardware
architecture visible to the user. I'm pretty sure larger IBM mainframes
have had some internal bus sizes of 64 bits and larger for years, even
though the architecture visible to the user only had 32 bit registers
and and 31 bit addresses at the time.
Since the introduction of IBM S/360 in the 1960's almost all processors
have been implemented using microcoding techniques, which means that the
choice of hardware physical bus and register sizes is a matter of
cost-performance trade offs rather than something uniquely dictated by
the logical architecture seen by the users.
Leif Rundberget wrote:
Be careful with like terms between the PC(intel) world and the mainframe
world. When someone says they have a 64-bit Intel server (Intel,
Solaris, AMD, etc.), it does not mean that the server can access an
address 64-bits long, the 64-bits refers to the width of the bus. So it
can transfer 64-bits in parallel.
Leif
John KcKown wrote:
And, just for fun, Sun has implemented a 128-bit filesystem in Solaris!
That means that a single filesystem can contain 2**128 bytes of data.
Good heavens! I think that most UNIX filesystems are either 32 or 64 bit
at present. But don't quote me on that.
--
John McKown
Senior Systems Programmer
HealthMarkets
Keeping the Promise of Affordable Coverage
Administrative Services Group
Information Technology
--
Joel C. Ewing, Fort Smith, AR[EMAIL PROTECTED]
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