Interphase Tech iSPAN User Manual
Page 210
PCI/PMC Technology
190
Interphase Corporation
• Buffers located between peripherals and the CPU that
allow multiple, high-speed peripherals to be attached to
the same PCI local bus
• Automatic configuration of system and expansion
boards.
Three sizes of PCI add-in boards are defined: long, short, and
variable short length. Systems are not required to support all
board types. To accommodate 5V and 3.3V signalling
environments and to facilitate a smooth migration path
between the voltages, three add-in board electrical types are
specified: a “5 volt” board which plugs into only 5V
connectors, a “universal” board which plugs into both 5V and
3.3V connectors, and a “3.3 volt” board which plugs into 3.3V
connectors only.
The PMC bus was designed for embedded environments. It
implements PCI bus logic in a daughtercard (mezzanine) form
factor.
CompactPCI is another PCI form factor which implements
PCI bus logic in a Eurocard 3U or 6U format with a high-
density connector. This form factor is used in environments
similar to the more traditional VME bus. The PCI Industrial
Computer Manufacturers Group (PICMG
®
) is currently
developing the CompactPCI standard.