At 04:04 PM 8/28/1998  Jim Meagher  wrote:
>
>Okay, I forgot about bus-mastering motherboards but it still doesn't change
>the basic statement I was making.  No matter which slot you plug a modem
>into, it will not affect the functionality of the card.
>>
>> Not always true, some motherboards have both bus-mastering &
>> non-bus-mastering PCI
>> slots.
>>
>> Richard Quilhot


What is ostensibly true may not be practically true.

In a computer with a PCI bus, the system BIOS allocates
all resources to all PCI devices whether they are on the
motherboard or in card slots. As the computer boots up,
the BIOS finds out what type of resources (I/O, Memory,
IRQ, etc.) each PCI device needs. The BIOS then allocates
the resources at it sees fit. The PCI devices cannot request
specific resources or in any other way control the resources
allocated by the BIOS.

Therefore, moving the PCI card to a different slot may cause
the system to allocate a different IRQ, I/O port or memory to
the card, thereby avoiding a problem with resource assignment.
Many PCI systems allow you to re-allocate PCI resources in
CMOS setup, so you don't have to shuffle cards to accomplish
this.

Furthermore, the shared PCI/ISA slot (the slot closest to the
PCI to ISA Bridge Chip) and the slot closest to the LocalBus
to PCI bridge chip(s) may cause various PCI adapters to
perform differently due to timing, contention, or interference,
depending on the relative positioning of the devices on the PCI
bus. Moving things around may alleviate the problem.

Therefore, it is reasonable to expect different results from
putting the PCI modem in a different PCI slot. Also, you
should verify the modem card meets the PCI 2.1 specification.
HTH.

Regards,

John Chin

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