PDF of this tutorialThe Peripheral Component Interconnect Industrial Computer Manufacturer’s Group (PICMG) developed the compact peripheral component interconnect (CompactPCI) specification in 1994. CompactPCI is a high-performance industrial bus based on the peripheral component interconnect (PCI) electrical standard. It uses the Eurocard form factor first popularized by VersaModule-Eurocard (VME). Compared to the standard PCI deskCenter computer, CompactPCI supports twice as many PCI slots (eight) on a single system bus. In addition, CompactPCI boards are inserted from the front of the chassis and can route input/output (I/O) through the backplane to the back of the chassis. These design considerations make CompactPCI ideal for telco environments.
| Features | VME | CompactPCI | PCI | Industry Standard Architecture (ISA) |
| Address Space (Physical) | 4 GB | 4 GB | 4 GB | 1 or 16 MB |
| Addressing Method | Geographic | Slot sensitive or geographic | Slot sensitive | Board locator technology (BLT) |
| Time Division Multiplex (TDM) | Bus and Bandwidth American National Standards Institute (ANSI)/VME International Trade Association (VITA) 6-1994 2048 time slots std. 4096 time slots ext. | H.110 4096 time slots | H.100 up to 4096 time slots | SCbus up to 2048 time slots |
| Central Processing Units (CPU) in System | Multiple | 1 (master) | 1 (master) | 1 |
| Maximum Number of Channels | 400 per CPU 800 with BLT | TBD | TBD | 96 |
| Hot Swap/Live Insertion | VITA 1.4-199 | PICMG hot swap | PCISIG hot plug | Not supported |
| Cabling Options | SCbus and I/O ribbon cables, ANSI/VITA backplanes | Rear I/O transition modules, H.110 embedded backplanes | Bracket I/O, H.100/SCbus ribbon cable | Bracket I/O, SCbus ribbon cable |
| System Bus Bandwidth | 40 to 80 Mbps | 132 Mbps | 132 Mbps | 8 Mbps |
| System Bus Bits | SCbus, CT Bus | SCbus, CT Bus | SCbus, CT Bus | Scbus |
Table 1. System Bus Comparison
