Re: Data rate on PCI/AGP

["John R Pierce" <pierce@hogranch.com>]

>Any comment to the following questions is helpful:
>
>- peak data rate on the 66MHz/32Bit PCI which is part of the AGP.
>- sustained data rate over a long period on this PCI.
>
>- sustained data rate on the AGP with the help of AGP2x features.

You don't state what total sustainable bandwidth you require so I'm going on
assumptions here.

Also, your wording is somewhat vague, but it sounds like you are talking about
reads from your device into main memory.

AGP is almost entirely optimized for write operations FROM main memory INTO
the AGP device.  I don't know what the peak READ speed is, but its likely not
twice the base 33MHz PCI rate.  The AGP 2X protocol is designed for 3D
graphics devices fetching short bursts from random offsets in a texture map
stored in typically around 8-16MB of main memory..  As far as I know, AGP2X is
ONLY invoked on main memory->AGP burst operations.

There are specialized server class systems with general purpose 64 bit wide
and/or 66MHz PCI busses today.  These might do what you want.   I don't think
the dedicated AGP slot on a 440BX class system will do it.

-jrp