Plz see comments inline below.
Dick
----- Original Message -----
From: "Eric Dittman" <dittman_at_dittman.net>
To: <classiccmp_at_classiccmp.org>
Sent: Sunday, October 28, 2001 5:34 PM
Subject: Re: VLB SCSI?
> > > 64-bit PCI cards will work in a 32-bit PCI slot. I've got a four-port
64-bit
> > > Ethernet card in a 32-bit PCI slot in one of my systems.
> > >
> > I really don't see how they could work, since the connector is not likely to
> > fit. I recently had a peek at the standard for PCI, and I didn't seen any
way
> > in which this could work.
>
> They have been designed from the start to be forward- and backward-
compatible.
> The 64-bit has a slot where the end of the 32-bit connector is located, and
the
> correct connector does not have a wide end. All the 32-bit connectors I've
seen
> have been the correct size (and I've seen a lot of them). A 64-bit PCI card
in
> a 32-bit slot steps down to 32-bit transfers. A 66MHz card in a 33MHz slot
steps
> down to 33MHz.
>
That wouldn't work too well when you need 99% of the bandwidth. The few 64-bit
cards I've seen up close don't seem to have a wide enough slit to allow them to
be plugged into a short PCI slot. The standard references to features such as
this one seemed quite iffy. I wish I could justify a current copy of the
standard. I just returned one to the local library, which had to get it on ILL.
>
> > Since there apparently aren't any serious SCSI boards being made for 32-bit
PCI
> > any longer, and since most fibrechanel and firewire boards are 64-bit, I'd
think
> > it desirable to have most PCI mothers support the 64-bit PCI, which,
according
> > to what I've read so far, does support the 32-bit cards. If you want the
250+
> > MBPs transfer rates, no short PCI slot is going to handle that. The 10Gb
> > ethernet will demand that the system process sustained, meaning for years
and
> > years, not just for bursts of a few hundred picoseconds, transfer rates of
> > 10Gb/sec, and who knows what will come along after that. What's more, it's
got
> > to work faster than all that at the system level, since the traffic has to
go
> > somewhere and the responses have to come from somewhere as well.
>
> I've seen 32-bit FC and firewire cards. I've seen FC cards that come in both
> 32- and 64-bit configurations, although the 32-bit cards I've seen look like
> they are the 64-bit version with only a 32-bit edge connector.
>
> I've never seen a 64-bit firewire card.
>
Perhaps that one wasn't firewire, but it was ADAPTEC. The FC is what has me
buzzed up right now and I've seen no 64-bit slots in motherboards offered
recently. I hadn't even considered an Apple product, and it may take a while
for me to accept that notion. I've certainly never seen a high-bandwidth card
of any sort for sale that wasn't a 64-bit card. The abundance of 64-bit cards
against the dearth of motherboards with 64-bit PCI slots is what I've been
focusing on. Surely ADAPTEC and others are selling their products into
something with full 64-bit capacity.
>
> > ALPHA boards aren't relevant any longer, are they?
>
> I think so. The Alpha will be around for a while, with EV7 on the way,
despite
> what some people think. Compaq announced the Alpha would be winding down, not
> stopping dead in its tracks.
>
Yes, but they're controlled by someone else, now, and they're a fickle master.
I'd put no faith in that statement at all.
> --
> Eric Dittman
> dittman_at_dittman.net
> Check out the DEC Enthusiasts Club at http://www.dittman.net/
>
>
Received on Sun Oct 28 2001 - 19:01:33 GMT