CardBus
The PCMCIA used the PCI electrical specification as the basis of a 32-bit, high performance bus interface that utilizes the existing PCMCIA connector and form-factor. CardBus, or PC-Card 32, adds bus mastering and high-speed, 32-bit data transfer capabilities to PCMCIA.

Differences between CardBus and PCI are driven first by the PCMCIA mechanical environment, and next by the need to make CardBus sockets backward compatible with PCMCIA R2.x cards. PCI compliant devices are not automatically compliant with CardBus. The table below summarizes the basic differences between PCI and CardBus.

An organization known as Yenta has been formed to help insure interoperability among chip, card, system and software manufacturers of CardBus products.

For additional information you might try the following:

PCMCIA Headquarters
2635 North First Street, Suite 209
San Jose, CA 95134 USA
Tel (408) 433-CARD (2273)
Fax (408) 433-9558
BBS: (408) 433-2270
EMAIL: office@pcmcia.org
URL: http://www.pc-card.com

PCMCIA European Chapter
Avenue Marcel Thiry 204
B-1200 Brussels, Belgium
Tel +32 2-774-9620
Fax +32 2-774-9690

Yenta
John McGrath
Intel Corporation
2111 NE 25th Street
Hillsboro, OR 97124
Phone: (503) 264-8433
FAX: (503) 264-6055
EMAIL: h_john_mcgrath@ccm.jf.intel.com

More information on Xilinx and PCMCIA.

Passive-Backplane PCI
(See also CompactPCI)
Passive-Backplane PCI (PBPCI) arose out of the industrial user's need to make off-the-shelf PC hardware more serviceable and easier to upgrade. This was achieved by defining a system where all add-in cards, including the mother board, plug into a passive backplane.

The PBPCI specification was designed to allow use of existing desktop ISA and PCI add-in boards in the backplane without modification. The physical specification allows both ISA and either 32- or 64-bit PCI connectors to exist on one side of the board. Backplanes with a dual-bus CPU connector, 1 to 4 PCI connectors and 6 to 15 ISA connectors are available today.

The signals on the PCI interface have the same pin numbers as a PCI expansion slot. In addition, separate REQ# and GNT# lines are provided for each PCI slot to support up to four bus masters in one system. Because PBPCI allows up to 9-in. traces on PCI signals, a PBPCI CPU must provide a separate clock driver for each PCI slot in order to meet the 2-nsec clock-skew limit.

For more information regarding CompactPCI or to order a complete specification, contact the PCI Industrial Computer Manufacturers Group at:

PICMG
301 Edgewater Pl. Ste. 220
Wakefield, MA 01880
Phone: (617) 224-1100
FAX: (617) 224-1239
EMAIL: picmg@rogerscom.com
URL: http://www.picmg.com

CompactPCI
(See also Passive Backplane PCI)
This is a passive backplane specification for PCI designed for industrial or embedded applications that require a more robust form factor. CompactPCI is electrically compatible with the PCI specification, allowing the use of existing PCI chipsets including Xilinx programmable logic and the LogiCORE PCI Interface.

CompactPCI cards are based on the 3U and 6U Eurocard industry standard formats. They use high-performance shielded, 2-mm-pitch pin-and-socket connectors that have lower capacitance than desktop-style PCI edge connectors. CompactPCI also specifies the use of 10-ohm stub-termination resistors on signal lines that reduce the effect of board circuits on bus loading. These differences allow a maximum of eight cards to be put into a single CompactPCI backplane without the need for a PCI-to-PCI bridge. Use of bridges, however, allows up to 256 CompactPCI backplanes in a single system.

CompactPCI defines some additional signals on top of the PCI specification to enhance system operation. These signals provide push putton reset, power supply status, System Slot identification and legacy IDE interrupt support features. The standard has provision for 32- and 64-bit interfaces, as well as 5V and 3.3V signalling. Provision for hat-swapping is also provided, but many things need to be worked out before that becomes a reality. A 32-bit mezzanine version and form factor is also defined for space constrained embedded applications.

For more information regarding CompactPCI or to order a complete specification, contact the PCI Industrial Computer Manufacturers Group (PICMG). Also see the CompactPCI home page at:

EMAIL: info@compactpci.com
URL: http://www.compactpci.com

IndustrialPCI
IPCI offers a passive-backplane version of PCI in Eurocard (3U and 6U) formats for 19-in rack-mounted systems without all of the additions imposed by CompactPCI. IPCI is 100% compatible with the PCI-SIG specification. It supports both 32- and 64-bit PCI through a single 240-pin connector. The connector has either right angle pins for backplane applications or straight-pins for a mezzanine stack-through configuration. It can support a maximum of five slots.

For more information regarding IPCI or to obtain a complete specification, contact the Standard Industrial PC Systems manufacturers group at:

SiPS e.V.
Krappmuehlstrasse 34
D-68165 Mannheim
Germany
TEL: +49 621 402012
FAX: +49 621 4321430
EMAIL: 100066.62@compuserve.com
URL: http://www.sjps.com

PCI Mezzanine Card (PMC)
PMC is an open standard that provides a slim, modularized mezzanine card family for low profile computer applications such as VME. By following the PCI electrical specification, it allows embedded computer designers to use readily available, low cost PCI components. Provision is made in the PMC standard to support a full 64 bit PCI bus implementation. The specification is described in Draft IEEE Spec P1386.1. All Xilinx PCI compliant devices and design files are suitable for PMC applications.

For additional information you might try the following:

VITA at 602-951-8866
EMAIL: info@vita.com
URL: http://www.vita.com

Small PCI (SPCI)
Originally called Small Form Factor (SFF) PCI, the SPCI specification is a mechanical definition for a card and connector scheme with a credit card sized footprint for portable and space restricted applications. It uses all of the PCI Revision 2.1 signal protocol, electrical and configuration definitions, except support for 64-bit transfers and JTAG.

There are many physical similarities between SPCI and PCMCIA cards. Both have the exact same footprint, however SPCI uses a 108-pin connector versus PCMCIA's 68. Two SPCI card thicknesses are defined; Type A cards are 5.0 mm thick and Type B cards are 10.5 mm, corresponding to PCMCIA's Type II and III cards, respectively. These tight form factors will benefit from smaller device packaging such as the TQ/VQFPs available from Xilinx.

The specification states that its intent "is to define cards that are installed at the point of manufacture" and hence do not include descriptions for protective covers. But since the specification indicates that covers are not prohibited, it remains to see whether or not SPCI will compete directly with PCMCIA or CardBus as a user-accesible form of system expansion.

SPCI supports 5-Volt, 3.3-Volt and universal cards through a keyed connector scheme. Keying provisions have also been made to exclude PCMCIA, JEIDA and DRAM cards without damaging connector interfaces.

Revision 1.0 of the specification was released by the PCI-SIG on May 1, 1996, and may be obtained from that organization. All Xilinx PCI compliant devices can be used in SPCI applications.