7/28/2019 Unit-2_6 (Processor Organization)

1/13

Processor Organization

1

7/28/2019 Unit-2_6 (Processor Organization)

2/13

Processor Organization

2

There are several components insidea CPU, namely, ALU, control unit,

general purpose register, Instruction

registers etc. There are several waysto place these components and

interconnect them.

7/28/2019 Unit-2_6 (Processor Organization)

3/13

Types of Processor Organization

3

Single Bus Organization

Multiple Bus Organization

7/28/2019 Unit-2_6 (Processor Organization)

4/13

Single Bus Organization

4

In Single Bus Organization, thearithmetic and logic unit (ALU), and all

CPU registers are connected via a

single common bus. This bus is internal to CPU and this

internal bus is used to transfer the

information between differentcomponents of the CPU.

7/28/2019 Unit-2_6 (Processor Organization)

5/13

Single Bus Organization (continued)

5

This organization is termed as singlebus organization, since only one

internal bus is used for transferring of

information between differentcomponents of CPU.

7/28/2019 Unit-2_6 (Processor Organization)

6/13

Single Bus

Organization

(continued)

6/30/2013Ankur Mittal6

7/28/2019 Unit-2_6 (Processor Organization)

7/13

Single Bus Organization (continued)

7

We have external bus or buses toCPU also to connect the CPU with the

memory module and I/O devices.

The external memory bus is also

connected to the CPU via the memory

data and address register MDR and

MAR.

7/28/2019 Unit-2_6 (Processor Organization)

8/13

Single Bus Organization (continued)

8

The number and function of registersR0 to R(n-1) vary considerably from

one machine to another.

They may be given for general-

purpose for the use of the

programmer.

7/28/2019 Unit-2_6 (Processor Organization)

9/13

Single Bus Organization (continued)

9

Alternatively, some of them may bededicated as special-purpose

registers, such as index registeror

stack pointers.

7/28/2019 Unit-2_6 (Processor Organization)

10/13

Single Bus Organization (continued)

10

In this organization, two registers, namelyY and Z are used which are transparent to

the user.

Programmer cannot directly access thesetwo registers. These are used as input and

output buffer to the ALU which will be used

in ALU operations. They will be used by CPU as temporary

storage for some instructions.

7/28/2019 Unit-2_6 (Processor Organization)

11/13

Single Bus Organization (continued)

11

For the execution of an instruction, weneed to perform an instruction cycle.

An instruction cycle consists of two

phase:1. Fetch cycle and

2. Execution cycle.

7/28/2019 Unit-2_6 (Processor Organization)

12/13

pre-specified sequence

12

Most of the operation of a CPU can becarried out by performing one or more of

the following functions in some pre-

specified sequence:

1.Fetch the contents of a given memory

location and load them into a CPUregister.

2.Store a word of data from a CPU register

into a given memory location.

7/28/2019 Unit-2_6 (Processor Organization)

13/13

pre-specified sequence (Continued)

13

3.Transfer a word of data from oneCPU register to another or to the ALU.

4.Perform an arithmetic or logic

operation, and store the result in aCPU register.