Replies to post #13440 on Dream Machine

[Bruce A Thompson]

Low-Profile PCI
Q: What is Low-Profile PCI?

A: Low-Profile PCI is a new PCI card standard for space-constrained system designs. The new form factors maintain the same electricals, protocols, PC signals and software drivers as standard PCI v2.2 expansion cards. They are also mechanically similar; however, Low-Profile PCI is an additional form factor that defines a shorter raw card and new mounting bracket for card retention. The Low-Profile PCI definition is an engineering change notice (ECN) to the conventional PCI specification, Revision 2.2. It will include a new section in the mechanical chapter to define the Low-Profile PCI raw card and mounting bracket.

Q: What is the difference between Low-Profile PCI and Mini PCI?

A: Low-Profile PCI and Mini PCI are two different initiatives that address different market needs. Low-Profile PCI will allow greater flexibility in desktop and server designs, and in some cases eliminate the need for riser cards. Mini PCI was developed specifically for integrated communications peripherals such as modems and network interface cards (NICs) in a mobile environment. Mini PCI provides flexibility for OEM/system integrators and is not intended for end-user installation.

Q: If Mini PCI is smaller than Low-Profile PCI, then why not use Mini PCI rather than define a new standard?

A: The smaller card dimensions for Mini PCI require more compact and higher density components than Low-Profile PCI. Mini PCI is a standard for integrated peripherals that targets small form-factor products such as notebook PCs, docking stations and printers. In addition to the small size, Mini PCI requires a new interface to the board and system. Low-Profile PCI leverages existing adapter-card designs. Many cards are already short in height to save cost and optimize PCB panel sizes. In many cases, the bracket drives the height of the card assembly and therefore, the height of the system design.

Q: How tall will the Low-Profile cards be compared to standard PCI adapter cards?

A: Low-Profile PCI should fit into systems as low as 3.350" [85 mm] without the use of riser cards.

Q: Are there various card lengths defined for Low-Profile PCI similar to short and long cards for standard PCI?

A: Low-Profile PCI has two card lengths defined for 32-bit cards, MD1 and MD2. The purpose of MD1 and MD2 is to establish size limits for system designers. MD1 is the shortest card offering and poses the greatest challenge to adapter-card vendors. However, MD1 cards also allow for the smallest system design. Systems which are designed to support both MD1 and MD2 card lengths will have the greatest flexibility in supporting all Low-Profile PCI compliant cards.

Q: Will Low-Profile PCI fit into current brackets?

A: Low-Profile PCI will be backward compatible for existing brackets; however, the ECN will also define a new bracket that will not be compatible with standard PCI cards.

Q: Is Low-Profile PCI going to support 5.0 volt signaling?

A: To reflect the PCI-SIG's market recommendation of moving to 3.3 volt signaling as quickly as possible, Low-Profile PCI will only support 3.3 volt signaling.

Q: What is the status of Low-Profile PCI?

A: The Low-Profile PCI ECN was officially approved and released by the steering committee on February 11, 2000. The Low-Profile ECN, along with all other ECNs to the v2.2 PCI bus specification, are currently available at the PCI-SIG Web site, www.pcisig.com, for free download to the industry.

Q: When will Low-Profile PCI products be available?

A: Compliant Low-Profile PCI products are currently on the market. Q-Logic is presently producing Low-Profile PCI products. Accton Technologies is also currently producing two products that support Low-Profile PCI, the EN1207D series 10/100 Fast Ethernet Adapter and the EN1207F series 10/100 Fast Ethernet Adapter.

Low-Profile has been rolled into the testing and certification at compliance workshops to allow vendors to bring compliant products to market.