Memory

Types of memory
1. PRIMARY MEMORY
2. SECONCERAY MEMORY

 PRIMARY MEMORY

• Directly Accessed By Microprocessor

• The MEMORY holds all of the "active" information that the Microprocessor is using
EX: RAM
RAM

• Random access memory
• It is an Semiconductor memory
• Accessed by microprocessor and peripherals
• All Programs executed in RAM ONLY.

CLASIFICATION :

MEMORY Can be classified as

PHYSICAL MEMORY
LOGICAL MEMORY
VERTUAL MEMORY.

RAM

• Random access memory
• It is an Semiconductor memory
• Accessed by microprocessor and peripherals
• All Programs executed in RAM ONLY.

CLASIFICATION :

MEMORY Can be classified as

PHYSICAL MEMORY
LOGICAL MEMORY
VERTUAL MEMORY.

PHYSICAL MEMORY:
Physically available
EX RAM

LOGICAL MEMORY:
Assigning addresses to MEMORY.

VERTUAL MEMORY
• IT’S a part of HARD DISK
• Treated as RAM
• Because it stores the program which are to be executed
• Not available to user to store any other DATA
• cache :
Cache is a small, high-speed memory that is placed between the processor and the system memory
TYPES OF RAM :

• SRAM
• DRAM

• SRAM:
• STATIC RAM
• Refreshing Rate is Low
• Uses array of transistors for each memory cell.

• DRAM
• The DRAM can only hold data for a short period of time and must be refreshed periodically.
• DRAMs are measured by storage capability and access time.
• Storage is rated in megabytes (8 MB, 16 MB, etc).
• Access time is rated in nanoseconds (60ns, 70ns, 80ns, etc) and represents the amount of time to save or return information.
• The lower the nanospeed, the faster the memory operates.
• FPMDRAM:
• This was the most common and was often just referred to as DRAM.
• It offered faster access to data located within the same row.
• EDO (Extended Data Out)
• Newer than DRAM (1995) and requires only one CPU wait state.
• 10 to 15% improvement in performance compared to FPMDRAM memory .

• SDRAM synchronous RAM)
• Introduced in late 1996
• It synchronizes itself with the timing of the CPU Clock.
• Transfers data on Rising Edge of Clock.
• SDRAM is faster and more expensive than DRAM.
• It comes in speeds of 66, 100, 133, 200, and 266MHz.

• RDRAM
• RAMBUS DYNAMIC RAM
• This memory is fastest memory operates at 800 MHZ
• Used in video Graphic Cards and Cache Memory.
• DDR-SDRAM :
• Double Data Rate Synchronous DRAM
• Allows transactions on both the rising and falling edges of the clock cycle.
• DDR RAM Faster SD RAM

• VRAM :
• VIDEO RANDOM ACCESS MEMORY
• Buffer memory between CPU and the Video Card
• Stores images that are to be displayed
• SIMM (Single In-line Memory Modules)
• SIMMs is used to store a single row of DRAM, EDO or BEDO chips where the module is soldered onto a PCB..
• The first SIMMs transferred 8 bits of data at a time and contained 30 or 72 pins.

• DIMM (Dual In-line Memory Modules)
• DIMMs allow the ability to have two rows of DRAM, EDO or EDO chips.
• DIMMs contain 168 pins
• Each Side 84 pins
• Transfer data in 64,72,or 80 bit .
• DIMMs install straight up and down and have two notches on the bottom of the PCB

• SODIMM (Small Outline DIMM)
• Smaller version of DIMM
• SO DIMMs are commonly used in notebooks and are smaller than normal DIMMs.
• There are 3 types of SO DIMMs.
• Either 72 pins and a transfer rate of 32 bits
• 144 pins with a transfer rate of 64 bits.
• 200 pins with a transfer rate of 64 bits
• SIMM (Single In-line Memory Modules)
• SIMMs is used to store a single row of DRAM, EDO or BEDO chips where the module is soldered onto a PCB..
• The first SIMMs transferred 8 bits of data at a time and contained 30 or 72 pins.

• DIMM (Dual In-line Memory Modules)
• DIMMs allow the ability to have two rows of DRAM, EDO or EDO chips.
• DIMMs contain 168 pins
• Each Side 84 pins
• Transfer data in 64,72,or 80 bit .
• DIMMs install straight up and down and have two notches on the bottom of the PCB

• SODIMM (Small Outline DIMM)
• Smaller version of DIMM
• SO DIMMs are commonly used in notebooks and are smaller than normal DIMMs.
• There are 3 types of SO DIMMs.
• Either 72 pins and a transfer rate of 32 bits
• 144 pins with a transfer rate of 64 bits.
• 200 pins with a transfer rate of 64 bits