PCI Bus Compatibility Question

Hello,

Would someone be so kind as to explain the fundamental differences
between PCI 64 and PCI Express? Is it likely that a PCI Express device
would function in a PCI 64 slot?

I'm currently involved in a low budget project to test some video
capture technologies. The test platform we have available is an IBM
eServer xSeries 350, which has several 64 Bit PCI slots. One device I'd
like to test is a PCI Express device.

This is likely a dumb question, but I've been focused on enterprise
application development for the past few years and have lost track of
developments in hardware. (At this point, I'm not sure if I could tell
the difference between a 5V and a low voltage 32 bit PCI card! Sad... I
know.)

Thanks in advance,

John

writes:
>
> Would someone be so kind as to explain the fundamental differences
> between PCI 64 and PCI Express? Is it likely that a PCI Express device
> would function in a PCI 64 slot?

They are fundamentally different. At the hardware level, they are
best described by saying they have nothing in common (I'm sure
somebody will point out something they share that I don't know
about... but not much).

PCI 64 is a 64-bit parallel bus. PCI-Express is a very fast serial
bus (with a notion of "lanes" to allow several of these serial
channels to operate in parallel).

There is no possibility whatever that a PCI-Express will work in a PCI
64 slot. I wouldn't be surprised to be told that they were careful to
make sure it wouldn't even fit in the slot, in order to make sure
nobody caused damage by trying it.
--
Joseph J. Pfeiffer, Jr., Ph.D. Phone -- (505) 646-1605
Department of Computer Science FAX -- (505) 646-1002
New Mexico State University http://www.cs.nmsu.edu/~pfeiffer

On 4 May 2006 09:10:37 -0700, wrote:

>Hello,
>
>Would someone be so kind as to explain the fundamental differences
>between PCI 64 and PCI Express? Is it likely that a PCI Express device
>would function in a PCI 64 slot?
>
>I'm currently involved in a low budget project to test some video
>capture technologies. The test platform we have available is an IBM
>eServer xSeries 350, which has several 64 Bit PCI slots. One device I'd
>like to test is a PCI Express device.
>
>This is likely a dumb question, but I've been focused on enterprise
>application development for the past few years and have lost track of
>developments in hardware. (At this point, I'm not sure if I could tell
>the difference between a 5V and a low voltage 32 bit PCI card! Sad... I
>know.)
>
>Thanks in advance,
>
>John

Fundamental Difference #1: PCI (all flavors) and PCI-X Mode 1 both use
single-ended, multi-drop interconnects, 32 or 64 bits in width. PCI Express
uses point-to-point low-voltage differential interconnects, 1, 2, 4, 8 or 16
bits in width.

There is no similarity between the connectors used for each. You cannot plug a
PCI Express card into a PCI or PCI-X connector, nor vice versa...

Cheers

/daytripper

That's about as clear an explanation as could be. This is the kind of
question that results when you allow systems analysts access to the...
oh... what do you call those things.... screwdrivers!

Thank you both.

John

writes:

> That's about as clear an explanation as could be. This is the kind of
> question that results when you allow systems analysts access to the...
> oh... what do you call those things.... screwdrivers!

I'm always careful to keep a screwdriver handy. I find the machines
are much less uppity when they know they could be dismantled at a
moment's notice... and who knows if they'd ever go back together
again?
--
Joseph J. Pfeiffer, Jr., Ph.D. Phone -- (505) 646-1605
Department of Computer Science FAX -- (505) 646-1002
New Mexico State University http://www.cs.nmsu.edu/~pfeiffer

Mechanical expertise is inversely proportional to the number of parts
left over after reassembly. Or, more philosophically: If the whole is
greater than the sum of its parts, then it thus follows that virtue
belongs to those who possess the active readiness to create more than
was before by assembling from the sum of the parts a whole... and
finding where all of the screws go.