PCI mezzanine card
Encyclopedia
A PCI Mezzanine Card or PMC is a printed circuit board
manufactured to the IEEE P1386.1 standard. This standard combines the electrical characteristics of the PCI
bus with the mechanical dimensions of the Common Mezzanine Card or CMC format (IEEE 1386 standard).
A mezzanine connector connects two parallel printed circuit boards in a stacking configuration. Many mezzanine connector styles are commercially available for this purpose, however PMC mezzanine applications usually use the 1.0mm pitch 64 pin connector described in IEEE 1386.
A PMC can have up to four 64-pin bus connectors. The first two ("P1" and "P2") are used for 32 bit PCI signals, a third ("P3") is needed for 64 bit PCI signals. An additional bus connector ("P4") can be used for non-specified I/O signals. In addition, arbitrary connectors can be supplied on the front panel, or "bezel".
The PMC standard defines which connector pins are used for which PCI signals; in addition it defines the optional 64 "P4" connector pins for use of arbitrary I/O signals.
It enables manufacturers to offer products that are compatible with the well-established PCI bus, but in a smaller and more robust package than standard PCI plug-in cards. The word mezzanine
, meaning a platform inserted between two floors of a building, describes the way in which a PMC card fits between two adjacent host cards in a standard card rack, attached to one of the cards by connectors and mounting pillars. A single PMC measures 74 mm x 149 mm. The standard also defines a double-sized card, but this is rarely used.
Carrier cards that accept PMCs are usually made in the Eurocard format, which includes single, double and triple-height VMEbus
cards, CompactPCI
(cPCI) cards and more recently, VPX
cards. One PMC fits on a standard 3U
carrier card while 6U
models (typical for VMEbus
cards) can carry up to two PMCs. PMCs were also used in early ATCA systems prior to the advent of the Advanced Mezzanine Card
or AMC.
For the PMC standard, I/O technologies account for much of the market, but various card functions are commercially available including Intel Architecture and PowerPC processors, graphics cards, and memory cards. I/O cards are available such as Serial communication
controllers, SCSI
controllers, Graphics controllers and Firewire controllers.
Printed circuit board
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
manufactured to the IEEE P1386.1 standard. This standard combines the electrical characteristics of the PCI
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...
bus with the mechanical dimensions of the Common Mezzanine Card or CMC format (IEEE 1386 standard).
A mezzanine connector connects two parallel printed circuit boards in a stacking configuration. Many mezzanine connector styles are commercially available for this purpose, however PMC mezzanine applications usually use the 1.0mm pitch 64 pin connector described in IEEE 1386.
A PMC can have up to four 64-pin bus connectors. The first two ("P1" and "P2") are used for 32 bit PCI signals, a third ("P3") is needed for 64 bit PCI signals. An additional bus connector ("P4") can be used for non-specified I/O signals. In addition, arbitrary connectors can be supplied on the front panel, or "bezel".
The PMC standard defines which connector pins are used for which PCI signals; in addition it defines the optional 64 "P4" connector pins for use of arbitrary I/O signals.
It enables manufacturers to offer products that are compatible with the well-established PCI bus, but in a smaller and more robust package than standard PCI plug-in cards. The word mezzanine
Mezzanine (architecture)
In architecture, a mezzanine or entresol is an intermediate floor between main floors of a building, and therefore typically not counted among the overall floors of a building. Often, a mezzanine is low-ceilinged and projects in the form of a balcony. The term is also used for the lowest balcony in...
, meaning a platform inserted between two floors of a building, describes the way in which a PMC card fits between two adjacent host cards in a standard card rack, attached to one of the cards by connectors and mounting pillars. A single PMC measures 74 mm x 149 mm. The standard also defines a double-sized card, but this is rarely used.
Carrier cards that accept PMCs are usually made in the Eurocard format, which includes single, double and triple-height VMEbus
VMEbus
VMEbus is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. It is physically based on Eurocard sizes, mechanicals and connectors , but uses its own signalling system,...
cards, CompactPCI
CompactPCI
A CompactPCI system is a 3U or 6U Eurocard-based industrial computer, where all boards are connected via a passive PCI backplane. The connector pin assignments are standardized by the PICMG US and PICMG Europe organizations. PICMG stands for PCI Industrial Computers Manufacturers Group...
(cPCI) cards and more recently, VPX
VPX
VPX, formerly known as VITA 46, is an ANSI standard that provides VMEbus-based systems with support for switched fabrics over a new high speed connector...
cards. One PMC fits on a standard 3U
Rack unit
A rack unit or U is a unit of measure used to describe the height of equipment intended for mounting in a 19-inch rack or a 23-inch rack...
carrier card while 6U
Rack unit
A rack unit or U is a unit of measure used to describe the height of equipment intended for mounting in a 19-inch rack or a 23-inch rack...
models (typical for VMEbus
VMEbus
VMEbus is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. It is physically based on Eurocard sizes, mechanicals and connectors , but uses its own signalling system,...
cards) can carry up to two PMCs. PMCs were also used in early ATCA systems prior to the advent of the Advanced Mezzanine Card
Advanced Mezzanine Card
Advanced Mezzanine Cards are printed circuit boards that follow a specification of the PCI Industrial Computers Manufacturers Group , with more than 100 companies participating. Known as AdvancedMC, the official specification designation is AMC.x . AdvancedMC is targeted to requirements for the...
or AMC.
For the PMC standard, I/O technologies account for much of the market, but various card functions are commercially available including Intel Architecture and PowerPC processors, graphics cards, and memory cards. I/O cards are available such as Serial communication
Serial communication
In telecommunication and computer science, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels...
controllers, SCSI
SCSI
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...
controllers, Graphics controllers and Firewire controllers.
Variants
Additional standards exist that define variants of the standard PMC. For example,- PMC-X (PCI-XPCI-XPCI-X, short for PCI-eXtended, is a computer bus and expansion card standard that enhances the 32-bit PCI Local Bus for higher bandwidth demanded by servers. It is a double-wide version of PCI, running at up to four times the clock speed, but is otherwise similar in electrical implementation and...
PMC) defined by the VITAVMEbusVMEbus is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. It is physically based on Eurocard sizes, mechanicals and connectors , but uses its own signalling system,...
39 standard - PPMC (aka PrPMC; processor PMC) defined by the VITA 32 standard. I.e. for allowing processors to have host or monarch, support on a PMC. Additional signaling is defined so that the PrPMC can work as the host processor on a PCI bus. The intention is to allow a monarch PMC to control the PCI bus. This is usually a requirement if the PMC is to act as a host processor module.
- CCPMC (conduction-cooled PMC) defined by the VITA 20 standard
- XMC, or Switched Mezzanine Card, (PMC with high-speed serial fabric interconnect) defined by the VITA 42 standard. XMC specifies a 5th connector ("P5") that supports PCI ExpressPCI ExpressPCI Express , officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP bus standards...
(VITA 42.3) or other high speed serial formats such as Serial RapidIORapidIOThe RapidIO architecture is a high-performance packet-switched, interconnect technology for interconnecting chips on a circuit board, and also circuit boards to each other using a backplane...
(VITA 42.2) and Parallel RapidIORapidIOThe RapidIO architecture is a high-performance packet-switched, interconnect technology for interconnecting chips on a circuit board, and also circuit boards to each other using a backplane...
(VITA 42.1).