On 10/13/2010 12:17 PM, H. Peter Anvin wrote:
>
> The ACPI specification recognizes three interfaces as standard: PC/AT
> (64 bytes, even though 128 bytes is available on a lot of platforms),
> PIIX4 (256 bytes), and Dallas Semiconductor ("256 bytes or more"). The
> interface for the latter isn't well cited in the ACPI spec, but I'm
> guessing this is referring to the DS17885 series of chips, which can
> have up to 8K CMOS using a bank-switched scheme which presents 128 bytes
> at a time (thus accessible via only the standard 70/71 ports.)
>
FWIW, the DS17885 scheme actually allows addressing up to 64K; 8K is the
maximum that DS produced with this particular interface as far as I
know, but there are 16 address bits available.
-hpa
