RE: New project...PCI based servo control board

["Craig Edwards" <cedwards-at-ceinetworks.com>]

My understanding is that we will see PCI-Express (the new "marketing" name
for 3GIO) based systems later this year, with broad adaptation not taking
hold till 2004.  But as I understand it, most systems will still carry
"standard" 3.3V PCI-X slots as well.  I agree that longer term (maybe as
soon as 2 years....), PCI slots will become scarce and serial interconnects
will rule.  We can investigate PCI-Express a little further, but really I
think it introduce a lot of variables into the project, not to mention that
most folks don't want or need to use a "new" PC for machine control.
Actually, you can still find lots of ISA slots out there, and that was
pronounced "dead" 3 or 4 years ago.

I think one of the main issues is the software interface, and fortunately I
think the PCI-SIG group has addressed that pretty well by keeping the same
programming interfaces.  Simplistically, you can think of PCI-Express as
"just" serial PCI.  So what ever work gets done on this project should
translate to the serial version pretty easily.  The following link is a
position statement by the PCI-SIG that goes into more detail on these
issues.  

http://www.pcisig.com/data/specifications/PCIExpress10FAQ.pdf

But I'm open to more discussion on this topic, I agree that we should
consider PCI-Express in our planning....:)

-Craig





High-Speed Buses: What is Beyond PCI?


I recall a while back discussions of a PCI bus type board.. I wonder what
has happened to that project..can someone enlighten us..The high price to
produce the board might be one reason the project has not progressed????.

The other reason why you should be carefull in developing a PCI bus
controller is that the next generation of PC will not have a PCI bus on the
motherboard.

Remember the EISA versus PCI versus VL-Bus wars? That battle ended with PCI
victorious. 

The current PCI bus is called the PCI-X standard. 
PCI-X is championed by three main players--Compaq, IBM, and HP.and , it
offers two new higher speeds, 100 MHz and 133 MHz., PCI-X will allow eight
33 MHz slots, four 66 MHz slots, two 100 MHz slots, or a single 133 MHz slot
per controller.

There are a plethora of players involved in replacing the PCI bus

1. InfiniBand, which stands for "infinite bandwidth", is one of the new
technologies that is not a direct PCI replacement (as is often assumed), but
is one of the most ambitious and complex of the new interconnects. With key
backing from Intel, Dell, Hitachi, Sun Microsystems, Hewlett-Packard, IBM,
and 3Com, InfiniBand is intended to be a specialized datacenter
server-to-server and server-to-storage interconnect, though it feels more
like a fully switched I/O networking architecture, than a traditional I/O
bus.

2. A consortium called the Arapahoe Group, led by Intel, Compaq, HP and
Microsoft, has recently proposed a new standard called 3GIO (Third
Generation I/O) for now, which is meant to replace PCI as both an expansion
bus and chip-to-chip interconnect, and provide backward software
compatibility with its PCI ancestor. The PCI-SIG will take over the
management and promotion of 3GIO.

3. Two other high-performance, low latency buses, Motorola's RapidIO
(originally announced by Motorola at the Embedded Systems Conference in
Spring 2000) and AMD's HyperTransport, are aiming squarely at the
communications and embedded market. AMD is also targeting chip-to-chip
communications in the server and desktop market as well, and you may already
know HyperTransport is used in Nvidia's Nforce chipsets, and in the Xbox as
the interface between its NV2A and MCP chipset components (with an Intel
processor right nearby.).

As you would expect, the RapidIO Interconnect Architecture and Trade
Association includes communications heavy hitters like Motorola, Cisco,
Lucent, Nortel Networks, and Xilinx. The HyperTransport Consortium is a mix
of communications and system players, including AMD, Apple Computer, Cisco
Systems, nVidia, API Networks, PCM Sierra, and Sun Microsystems.

All these future interconnects and buses have a few things in common. They
use packet-based, point-to-point connections; in fact, InfiniBand implements
a full switch fabric. They provide bandwidth in multiples of that offered by
PCI. 

Having two competing bus structures--three, if PCI itself continues to
evolve--will put us back into the EISA/PCI/VL-Bus days of old.

So consider the above before you commit to a PCI design.

ps.. if you decide to proceed I will be glad to help...
Alex Kovacic
FISH Lab
CYTOGENETICS UNIT,
SEALS,Level 4, Campus Centre,
Prince Of Wales Hospital,
RANDWICK, NSW, 2031,
AUSTRALIA,
Tel: (61) (02) 9382 9168
Fax: (61) (02) 9382 9157
email1:A.Kovacic-at-unsw.edu.au
email2:kovacica-at-sesahs.nsw.gov.au