Re: The history of the Linux OS
Daniel Engstrom (danne@lillfab.se)
Fri, 27 Nov 1998 11:14:47 +0100 (CET)
On 26 Nov, Brandon S. Allbery KF8NH wrote:
> In message <199811261356.OAA07082@www.lillfab.se>, Daniel Engstrom writes:
> +-----
> | Or the engineer at IBM who decided that only decoding the low 10 bits
> | for i/o port accesses was enough for all future.
> +--->8
>
> The 8086/8088 only had 10 bits of I/O addressing, IIRC. The limitation on
> 80286+ was probably intended to avoid aliasing problems with 8-bit cards.
Nope it have always been 16 bits. The reason for going with 10 bits was costs saving.
(Not that they saved that much, they could just have ORed together the
6 high address lines with AEN to make an IOAEN signal on the ISA bus.)
/Daniel
--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/