[ The PC Guide | Systems and Components Reference Guide | Motherboard and System Devices | System Buses | System Bus Types | Peripheral Component Interconnect (PCI) Local Bus ]

PCI Expansion Slots

The PCI bus offers more expansion slots than most VLB implementations, without the electrical problems that plagued the VESA bus. Most PCI systems support 3 or 4 PCI slots, with some going significantly higher than this.

Note: In some systems, not all of the slots are capable of bus mastering. This is now far less common than it was, but with early systems the motherboard manual should be checked to see if this is the case.

The PCI bus offers a great variety of expansion cards compared to VLB. The most commonly found cards are video cards (of course), SCSI host adapters, and high-speed networking cards. (Hard disk drives are also on the PCI bus but are normally connected directly to the motherboard on a PCI system). However, it should be noted that certain functions cannot be provided on the PCI bus. For example, serial and parallel ports must remain on the ISA bus. Fortunately, the ISA bus still has more than enough speed to handle these devices, even today.

Next: PCI Internal Interrupts

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