Friday, 7 December 2012

Memory Interfacing in 8085 Microprocessor

Memory Interfacing:-As we know that any system which process digital data needs the facility for storing the data. Interfacing is a technique to be used for connecting the Microprocessor to Memory.

Now a days Semiconductor memories are used for storing purpose. There are some of the advantages of the
 semiconductor memory.

Small size
High speed
Better reliability
Low cost

Generally, RAM or ROM is used for memory interfacing.

Memory:-A memory is a digital IC which stores the data in binary form.

Memory Size:-The number of location and number of bits per word will vary from memory to memory. For example, If a particular memory chip is capable of storing M words with each word having N-bits. Then the size of the memory will be M× N.

Interfacing a ROM memory of 4096*8 with 8085 Microprocessor:-

Given memory size = 4096 * 8
4096 =2^12.
So 12 lines will be used for interfacing. A0 to A11

In this system A0 to A11 lines of Microprocessor will be connected to the address lines of the memory. and D0 to D7 of the 8085 microprocessor will be connected to the data bus of the memory.
As we know that the it is EPROM, so only RD pin is connected to the microprocessor. There is not the facility for writing data.

In case if you are using RAM then you have to connect one more pin for writing operation.


As you can see that there is a pin named CS. Generally this pin is used for Selction for the chip in case of two or more than memory chip. 
Latch has been used to separate the data and address bus.