Common Bus System | CSO

Common Bus System

The basic computer has eight registers, a memory unit and a control unit, If information is transfer from one register to another register or memory to register than a Common Bus System is provided for this scheme.

Working of Common Bus System

We understand the working of common bus system.Before understanding the working of common bus system let we know about registers used in common bus system.

• DR (Data Register)
  It is a 16-bit data register.It can hold memory operand.
• AR (Address Register)
  It is a 12-bit address register.It can hold memory address.
• AC (Accumulator)
  It is a 16-bit accumulator.It is used as process register.
• IR (Instruction Register)
  It is a 16-bit instruction register.It can hold instriction code.
• PC (Program Counter)
  It is a 12-bit program counter.It can hold address of next instruction.
• TR (Temperory Register)
  It is a 16-bit temperory register.It can hold temperory data.
• INPR (Input Register)
  It is a 8-bit input register.It can hold input character.
• OUTR (Output Register)
  It is a 8-bit output register.It can hold output character.

Now suppose output of DR=3 i.e the 16-bit output DR are placed on bus lines where S2S1S0=011, since this ia the binary value of decimal3. The lines from the common bus are connected to the input of each register and the data input to the memory. The particular register whose LD (load) input is enabled received the data from the bus during the next clock pulse transition.The memory recieve the content of bus when its write input is activated.

The memory plan 16-bit output onto the bus when read input is activated and SS0S1=111.

AR & PC are 12-bit when the content of AR or PC are applied to the 16-bit common but for most significant bit are set to 0's.

Know More>>>

• Introduction of Computer Organization
• Addressing Mode
• Common Bus System
• Control Unit
• Type of Instructions

Content is Reference form Compute System Architecture, MORRIS M. MANO