Bus width VS bus bandwidth

Many people confuse the width of the computer bus with the bandwidth of the bus, but in fact, they are different.

Bus Width: Bus Width generally refers to the internal bus binary digits interconnected between the CPU’s calculator and memory, affecting throughput, as described belowbus width。

Bus bandwidth: Bus bandwidth refers to the total amount of data that the bus can transmit in a unit time, equal tobus widthThe product of the work frequency is the bus bandwidth.Data transmission rate。

For example:

Bus width is 32 bits, clock frequency is 200 MHz, if the bus every five clock cycles to send a 32 bit word, ask how much bus bandwidth?

Answer:

According to the bus clock frequency200MHz，

have to1 The clock cycle is1/200MHz=0.005μs 

The bus transmission cycle is0.005μs×5=0.025μs 

Because the width of the bus is32 Bit =4B (byte)

BusData transmission rateby4B/（0.025μs）=160MBps 

 

PS：The bus cycle usually refers to the time required for CPU to complete a MEM or I/O port operation. A bus cycle consists of several clock cycles.