Random access memory

RANDOM ACCESS
MEMORY
CREATED BY:-
Anik Mazumdar

Index:
 Introduction.
 History.
 Technologies.
 Block Diagram.
 Position & Structure.
 Types of Ram.
 Difference.
 Capacity to store.
 Manufacturing companies.
 Advantage & Disadvantage

Introduction:
 Random access memory (RAM) is the best known form of computer
memory.
 RAM is considered as volatile memory, which means that the stored
information is lost when there is no power.
 RAM is made up of small memory chips that form a memory module.
 Whenever you open a program, it gets loaded from the hard drive
into the RAM.
 This is because reading data from the RAM is much faster than
reading data from the hard drive

History:
 RAM (Random Access Memory) was invented by Robert Heath
Dennard.
 At IBM Thomas J Watson Research Center in 1968.

Block Diagram Of Ram:
2k x n memory
ADRS OUT DATA CS
WR

Block Diagram Of Ram:
 This block diagram introduces the main interface to RAM.
 A Chip Select, CS enables or disables the RAM.
 ADRS specifies the address or location to read from or write to.
 WR selects between reading from or writing to the memory.
 To read from memory, WR should be set to 0.
 OUT will be the n-bit value stored at ADRS.
 To write to memory, we set WR = 1.
 DATAis the n-bit value to save in memory.

Types Of Ram:
Random Access Memory.
 SRAM (Static Random Access Memory).
• Static Random Access Memory.
• SRAM holds data in a static form, as long as the memory has power.
• Each bit is stored on four transistor that forms two cross coupled inverters.
 DRAM (Dynamic Random Access Memory).
• DRAM is called dynamic because it must constantly be refreshed and lose
the data in very short time.
• DRAM stores each bit of data in a separate capacitor within a integrated
circuit.

Capacity Of Ram
 From Beginning:
1. 256 MB
2. 512 MB
3. 1024 MB (1 GB)
4. 2048 MB (2 GB)
5. 4096 MB (4 GB)
6. 8192 MB (8 GB)

Manufacturing companies:
 ASUS.
 Buffalo Technology.
 Century.
 CEON.
 CHAINTECH.
 ELIXIR.
 HP.
 IBM.

Advantage:
 Programs will load much faster.
 Power Efficient, that uses much less power than disk drives.

Disadvantage:
 Volatile: a power outage will cause irrecoverable data loss.
 Space-limited: cost per bit is high.

Random access memory

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Random access memory