Ans-:
Von
Neumann Model
It was developed
in 1945 by John Von Newmann.Von Neumann model consist of a CPU, memory and I/O
devices. The program is stored in the memory. The CPU fetches an instruction
from the memory at a time and executes it.
The Von Neumann
architecture is a design model for a stored-program digital computer that uses
a processing unit and a single separate storage structure to hold both
instructions and data.
A.
Central Processor Unit [CPU]:
Central processor
unit consists of two basic blocks:
The program
control unit has a set of registers and control circuit to generate control
signals. The execution unit or data processing unit contains a set of registers
for storing data and an Arithmetic and Logic Unit (ALU) for execution of
arithmetic and logical operations. In addition, CPU may have some additional
registers for temporary storage of data.
B.
Input Unit:
With the help of
input unit data from outside can be supplied to the computer. Program or data
is read into main storage from input device or secondary storage under the
control of CPU input instruction. Example of input devices: Keyboard, Mouse,
Hard disk, Floppy disk, CD-ROM drive etc.
C.
Output Unit:
With the help of
output unit computer results can be provided to the user or it can be stored in
storage device permanently for future use. Output data from main storage go to
output device under the control of CPU output instructions.
Example of output
devices: Printer, Monitor, Plotter, Hard Disk, Floppy Disk etc.
D.
Memory Unit:
Memory unit is
used to store the data and program. CPU can work with the information stored in
memory unit. This memory unit is termed as primary memory or main memory
module. These are basically semiconductor memories.
There are two types
of semiconductor memories -
· Volatile Memory:
RAM (Random Access Memory).
· Non-Volatile
Memory: ROM (Read only Memory), PROM (Programmable ROM) EPROM (Erasable PROM),
EEPROM (Electrically Erasable PROM).