Control Bus: The physical connections that carry control information between the CPU and other devices within the computer. Whereas the data bus carries actual data that is being processed, the control bus carries signals that report the status of various devices. For example, one line of the bus is used to indicate whether the CPU is currently reading from or writing to main memory. (Webopedia.com)
Industry Standard Architecture (ISA) This architecture was originally used in the IBM PC/XT and PC/AT used for connecting peripheral devices. It has been made obsolete by PCI.
Peripheral Component Interconnect (PCI) Developed by Intel Corporation. It is a standard for local bus. It has a throughput rate of 133MBps.
Accelerated Graphics Port (AGP) A standard for 3-D graphic interfaces. Its first incarnation had a bandwidth of 266MBps with 2x, 4x, and 8x versions later following. The x is how many times 266MBps set bandwidth is (2x would be 533MBps, etc.). AGP ports are still common but are quickly being made obsolete by PCI Express.