>>>>> "Christophe" == Christophe Kumsta <[EMAIL PROTECTED]> writes:
Christophe> Kulwinder Atwal wrote:
>> AGP is meant to allow a card to use system memory, instead of
>> having to add more memory to the card. AGP allows the card's
>> processor (ie. video processor) to bypass the CPU and directly
>> access main memory. This allows a CPU to do more important things
>> with its time.
>>
Christophe> I don't think that's really right, cause the usage of
Christophe> memory directly from PCI is available too. It's called
Christophe> bus-master transfert ( from or to the PCI-card ), and
Christophe> this operation is done without main CPU.
Christophe> The first advantage of AGP bus is that this one can be
Christophe> considered as 'a second' PCI bus with only one peripheral
Christophe> ( this explain the full bandwith operation for one slot )
Christophe> and the frequency of the bus which is 66MHz against 33MHz
Christophe> for the PCI.
Of course there are 66 MHz PCI buses around, real ones. And if you
want the benefits of one device (no sharing of bandwidth) you can just
leave the other slots empty. 66 MHz PCI systems aren't all that
common among PCs but there are some (the SGI boxes, for example) and
are increasingly common in other platforms.
I view AGP as another EISA, a single-purpose hack for video cards
whose only real benefit is that it's cheaper than a faster real bus.
Then again, I may be cynical and/or uninformed.
paul
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