Sunday, June 19, 2022

Design of a 4*4 Random Access Memory (RAM)



What is Memory -

- A physical device capable of storing information

- Temporary information storage - RAM ( Information gets lost on Power Down)

- Permanently information storage - Read Only Memory (ROM)

- Memory devices are made of integrated circuits and are used by hardware , operating systems and softwires

- Three main processes involved in Memory : Encoding , Storage and Retrieval

Design of Memory Unit -

- A Memory Unit is a collection of storage cells together with their associated integrated circuits to transfer information in and out of the memory device.

- Below is the top level block diagram of a Memory Unit




- The construction of a M*N (M Words with N Bits Per Word) consists of M*N Binary Storage Cells and associated decoding circuits for selecting individual words

Binary Cell -





- The 'Select' input Enables the Cells for Reading or Writing

- Read/Write Bar == 1, Reading the Binary Cell by Making a Path Between Flip-Flop to Output

- Read/Write Bar == 0, Writing the Binary Cell by forming a Path from Input to flip-Flop

Design of a 4*4 Memory -






- 4*4 Memory with 4 Word Lines of 4 Bits each with a total of 16 Binary Storage Cells

- 2 Address Lines are needed for a 4 words memory

- Address lines are decoded using a Decoder with 'Memory Enable' signal

- Once a particular word line is 'selected', the 'Read/Write bar' signal determines the memory operation


Thank !

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