What is random access memory, Computer Engineering

Assignment Help:

Q. What is Random Access Memory?

We will discuss RAM as an example of sequential circuit. A memory unit is a collection of storage cells or flip flops along with associated circuits needed to transfer information in and out of device. The access time and cycle time it takes are constant and independent of location therefore the name random access memory.

172_What is Random Access Memory.png

Figure: Binary Cell

RAMs are arranged (logically) as words of fixed length. Memory communicates with other devices by data input and output lines and address selection lines and control lines which specify direction of transfer.

Now let's try to understand how data is stored in memory. The internal construction of a RAM of 'm' words and 'n' bits per word comprises m ×n binary cells and connected circuits for detecting particular words. Figure below displays logic diagram and block diagram of a binary cell.

The input is fed to AND gate 'a' in complemented form. Read operation is denoted by 1 on read/write signal. Thus during read operation only 'AND' gate 'c' becomes active. If cell has been selected then output will become equivalent to state of flip flop it implies that data value stored in flip flop is read. In write operation 'a' & 'b' gates become active and they set or clear J-K flip flop relying upon input value. Please note in case input is 0 then flip flop will go to reflected in state of flip-flop. So we say that input data has been stored in flip-flop or binary cell.

Figure below is extension of this binary cell to an IC RAM circuit where a 2×4 decoder is used to select one of the four words. (For 4 words we require 2 address lines) Please note that every decoder output is connected to a 4 bit word and read/write signal is given to every binary cell. Once decoder selects word, read/write input tells operation. This is derived using an OR gate since all non-selected cells will generate a zero output. When memory select input to decoder is 0 none of words is selected and contents of cell are unchanged irrespective of read/write input.

1320_What is Random Access Memory1.png

Figure: 4 × 4  RAM


Related Discussions:- What is random access memory

Data, Data, information and knowledge - Information System The nature ...

Data, information and knowledge - Information System The nature of information can most easily be defined in the context of its relationship to data and knowledge. Bohn (1994)

A global variable is a variable, A global variable is a variable A globa...

A global variable is a variable A global variable is declared outside the body of each function.

Compiler software difficulty, IA-64 instead depends on the compiler for thi...

IA-64 instead depends on the compiler for this task. Even before the program is fed into the CPU, the compiler studies the code and makes the similar sorts of decisions that would

#title., REPRESENTATION OF POYNOMIAL OF 2 OR MORE VARIABLES USING ARRAY

REPRESENTATION OF POYNOMIAL OF 2 OR MORE VARIABLES USING ARRAY

Cascade delete options, Create a relationship among Employee and Sales tabl...

Create a relationship among Employee and Sales tables using Emp No. Enforce referential integrity and select both cascade update and cascade delete options. Save the relationship.

Evaluation function - canonical genetic algorithm, Evaluation function - ca...

Evaluation function - canonical genetic algorithm: However note that this termination check may be related or the same as the evaluation function - that discussed later - but

Explain services of application layer., Explain services of Application Lay...

Explain services of Application Layer. Application Layer: As the highest layer within the OSI reference model, the application layer gives services to the users of OSI env

Illustrate the advantages of register transfer, Register Transfer We as...

Register Transfer We assign computer registers by capital letters to denote function of the register. Such as, the register which holds an address for memory unit is usually

Explain transport layer of osi model, Explain Transport Layer of OSI Mode...

Explain Transport Layer of OSI Model. The transport layer utilizes the services provided through the network layer, as best path selection and logical addressing, to give end

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd