Another term for the expansion slots on a computer’s motherboard is bus slots. A number of different bus architectures have been developed over time. For the A+ Exam, you need to be able to identify the differences between each of these bus architectures and know which ones are more popular today.
| Architecture | Bus Width (In Bits) | Speed |
| PCI | 32/64 | 33 MHz |
| AGP | 32 | 66 MHz (1x), 133 MHz (2x), 266 MHz (4x), 533 MHz (8x) |
| PCMCIA (laptops) | 16 | 33 MHz |
| PCI-X | 32/64 | 66/133/266/533 MHz |
| PCIe | Serial | Uses multiple lanes with each lane carrying 250 MBps. As an example, a PCIe x1 slot can carry data at 250 MBps, while a PCIe x4 slot can carry data at 1 GBps. PCIe version 2 doubles those transfer rates. |
| miniPCI | 32 | 33 MHz |
