Bus Structures

for a comp to archieve its operation, the functionnal units need to communicate with eah other.They need to be connected

group of parallel wires used to connect the functional units is called a bus

Each bus can transfer one bit of data

no of wire = len(word)

bus: connecting path for several devices

there is data bus, addr bus, control bus,etc

• if it was a single bus structure all units are connected to a bus so only one transfer at a time,only 2 device can communicate at a time

  • single bus is the simplest form of a abus

  • multiple buseds have concurrency in operation better performation but expensive

-Drawbacks

• The devices connectted to a bus vary widely in their speed of operation

  • devices relatively slow (printer, keyboard)

  • fast(optical disc)

  • faster(memory, processor)

• to cope with it:

  • a common approach is to include buffer regisrers with the device to hold the info during transfers

  • two-bus sructure/multiple-bus structures

Questions

the main virtue for using single bus structure is - cost effective

multiple buses and buffer registers - are used to overcome diff in data transfer speeds of various devices