>
> > On the PC architecture, ISA bus devices only decode the bottom
> > 10 bits of the IO address space.
>
> Sorry, this simply is not true.
it's true for 8-bit ISA. not for 16-bit.

i have 8-port card which i set to 0x1100 port base with dips and it works.

> For a counter example see the "USR ISDN Sportster TA intern" cards, driven by
> sys/dev/isa/isic_isa_usr_sti.c. I have such a card and it definitively works.
> It uses the following offsetts
>
> #define USR_HSCXA_OFF   0x0000
> #define USR_HSCXB_OFF   0x4000
> #define USR_INTL_OFF    0x8000
> #define USR_ISAC_OFF    0xc000
>
> from it's base IO port for different chips (or parts of chips) on the card.
>
> Martin
>

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Instead of asking why a piece of software is using "1970s technology,"
start asking why software is ignoring 30 years of accumulated wisdom.