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

Find sop expression, A. F(X, Y, Z) = ∑(0, 1, 2, 6, 7) using TRUTH TABLE onl...

A. F(X, Y, Z) = ∑(0, 1, 2, 6, 7) using TRUTH TABLE only B. F(X,Y,Z) = ∑ (4,6,7,8) + D(2,5,11,12) using K-Map 1. Find SOP expression 2. Simplify SOP expression 3. Implem

What is the maximum number of fragments, What is the maximum number of frag...

What is the maximum number of fragments that can result from a single IP Datagram? Explain. To fragment a datagram for transmission across a network, a router utilizes the netw

Why a function should have at least one input, Why a function should have a...

Why a function should have at least one input? There is no strong reason for this in verilog. I think this restriction isn't removed fin SystemVerilog. Some requirements where

Address - operand data types, Q. Address - operand data types? A...

Q. Address - operand data types? Addresses : Operands residing in memory are specified by their memory address while operands residing in registers are specified by a re

What does formal verification mean, What does formal verification mean? ...

What does formal verification mean? Formal verification uses Mathematical techniques by proving the design by assertions or properties. Correctness of the design can be achiev

What is open addressing, Open addressing:  The easiest way to resolve a co...

Open addressing:  The easiest way to resolve a collision is to begin with the hash address and do a sequential search by the table for an empty location. The idea is to place the

Define router, A router is used to Distributes information among networ...

A router is used to Distributes information among networks.

Determine the address when network address prefixed by 1000, A network addr...

A network address prefixed by 1000 is? A network address prefixed through 1000 is Class B address.

What is the working set of a process, What is the working set of a process?...

What is the working set of a process? The set of pages that are referred by the method in the last "n", references, where "n" is called the window of the working set of the pro

Detail explanation of cryptographic modules, Detail explanation of Cryptogr...

Detail explanation of Cryptographic modules Physical security of the cryptographic modules is also built in order to provide total security of the whole system and protect from

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