CHAPTER 5:BUS SYSTEMS

CHAPTER 5:BUS SYSTEMS

1. DATA BUS

   • -A path for moving data among system modules
   • -The width of the data bus is a key factor in determining overall system performances.

2. ADDRESS BUS

   • -Used to designate the source of destination on the data bus.
   • -Carries addresses from register to memory

3. CONTROL BUS

   • -Control signals transmits command and timing information among system modules
   • -Timing signals indicate validity of data and address information
   • -Command signals specify operations to be performed

4. INTERNAL AND EXTERNAL BUSES

   • INTERNAL BUS
     • -Located within a CPU chip for communication among the components in CPU chip
   • EXTERNAL BUS
     • -Supported by third party hardware and software

5. BUS HIERARCHY

   • Processor Bus
     • bus that the chipset uses to send information to and from the processor. 
   • Cache Bus
     • bus for accessing the system cache.
   • Memory Bus
     • Second-level system bus that connects the memory subsystem to the chipset and the processor
   • Local I/O Bus
     • High-speed input/output bus used for connecting performance-critical peripherals to the memory, chipset, and processor.
   • Standard I/O Bus
     • Used for slower peripherals (mice, modems, regular sound cards, low-speed networking) and also for compatibility with older devices

6. CHARACTERISTICS OF BUS

   • Bus width
     • Number of bit that can travel in parallel down the bus
   • Bus speed
     • It reflects how many bits of information can be sent accros wire each second
   • Bus bandwidth
     • total amount of data that can theoretically be transferred on the bus in a given unit of time.

7. PERIPHERAL COMPONENT INTERCONNECT(PCI)

   • A popular high bandwidth, processor independent bus that can function as a mezzanine or peripheral bus
   • Delivers better system performance for high speed I/O subsystems
   • PCI Special Interest Group (SIG)
   • PCI Express (PCIe)