RE: [SI-LIST] : AGP Buffer strengths

Elias Lozano (elias@3dfx.com)
Wed, 19 Nov 1997 17:31:29 -0800

I have the same concern as well. AGP is about 1/2 PCI and I would think
that having same buffers to meet both specs will cause these problems.

Any ideas as to what other people are doing will be appreciated.

thanks

Elias

>----------
>From: Rick Tan[SMTP:tan@apple.com]
>Sent: Wednesday, November 19, 1997 3:59 PM
>To: si-list@silab.Eng.Sun.COM
>Subject: [SI-LIST] : AGP Buffer strengths
>
>Has anyone looked at the strengths of AGP Buffers?
>
>Since AGP is a point to point bus, shouldn't the drivers be a lot weaker
>than they are currently?
>
>Looking at the specs, it seems that AGP buffers are 75% the strength of the
>weakest PCI 3.3 buffers, and 55% the strength of the strongest PCI 3.3
>buffers.
>
>Simulating a AGP bus 9.6 inches long (5.6 on the motherboard, and 4 on the
>add-in card) with the strong AGP drivers causes tremendous overshoot and
>undershoot (this is with the minimum clamping currents).
>
>Rick Tan (408) 974-1062
>
>
>