- Printed metal traceses on the motherboard or circuit board called as bus lines.
- CPU communicates with other devices on motherboard like memory, expansion cards, co-processor and keyboards via bus lines.
- Data is in the form of electrical signals either low current zero or high current one.
- Set of parallel buses is like highway for the data, which increases the computer performance.
- Simplifies the design of the motherboard.
- Reduces the circuitry and the cost.
Types of buses
- Is a path that connects the CPU, memory and other devices on the motherboard.
- Data is transferred form one system component to another using these lines.
- More number of bus lines increases the speed of data transfer because each bus line can transfer one bit at a time.
- The number of bit processor determines the value of data bus i.e. 32-bit processor has 32-bit data bus.
- Is same like data bus.
- Connection is between CPU and RAM and carries memory address instead of data.
- Number of address bus lines determines maximum number of memory address.
Bus has four communication standard
ISA (Industry Standard Architecture):
- 8 bit or 16 bit wide.
- Transfer 16 bit at a time with 98 slots black in color.
- It has speed up to 8-40 Mhz.
EISA (Extended ISA):
- ISA cards works on EISA slots and supports plug and play.
- Automatically configures adaptor cards by simply plugging in.
- Transfers 32 bit of data at a time.
- Brown in a color and has 188 slots.
PCI (Peripheral Component Interconnection):
- Can transfer 32 or 64 bit data at a time.
- Speed up to 38-48 MHz with 120 slots.
- White in a color and supports plug and play.
USB ( Universal Serial Bus):
- Speed varies between 12 MBPS to 4.3 GBPS depending on version 1.0, 2.0, 3.0.
- Supports plug and play, hot plugging etc.
There are also two other types of buses
Control Bus - It determines whether the data should be written or read from the data bus.
Expansion Bus - Used to connect the computer’s peripheral devices such as modem, printer and scanner with the CPU.