Random Access Memory Team Members: Aditya vaingankar Aneel Chandan Gupta Pallvi Sharma Richa Rashmi

Introduction Best known form of computer memory Allows data items to be accessed in almost the same amount of time irrespective of the physical location of data inside the memory Volatile type of memory Considered random access because any memory cell can be accessed directly if the row and column that intersect at that cell are known

Types of ram Two main forms are: 1. SRAM(Static RAM)-used primarily for cache. A bit of data is stored using the state of a six transistor memory cell. 2. DRAM(Dynamic RAM)-predominant form of computer memory used in modern computers. Stores a bit of data using a transistor and capacitor pair, which together comprise a DRAM memory cell.

Types of memory modules SIMM – Single inline memory module: The first variant of SIMM has 30 pins and provides 8 bits of data. The second variant of SIMM has 72 pins and provides 32 bits of data.

Types of memory modules DIMM - Dual inline memory module: DIMMs have twice as many pins compared to SIMMs. DIMMs eliminated the practice of pairing two SIMMs as one.

Functionality of RAM A memory unit is a collection of storage cells together with the associated circuits needed to transfer information in and out of the device. Memory cells can be accessed for information transfer to or from any desired location hence the name random access memory.

The basic unit of memory is bits i.e. 1 and 0 Most computer units use words for data transfer. The communication is achieved with the help of data input and output lines.

A generic block diagram of a memory unit

N specifies the data input/output lines providing the data to be stored The k address lines provides the word to be selected Read/write are control inputs Each word in the memory is assigned to an identification number called address.

2^k-1 words where k is the number of address lines. For example consider a capacity of 1k words of 16 bits each 1k=1024=2^10. So the allocation is 2048 bytes (16 bits make 2 bytes).

Read/write operation Write-transfer the binary address of the desired word to the address line. Read-transfer the data bits to be stored in memory to the data input lines. Read/write=0 –write to selected word Read/write=1 –read from selected word

Things to be taken care of Points to be considered before buying or upgrading RAM: QVL – Qualified Vendors List: Make sure you buy RAM that is on your motherboard’s QVL to ensure maximum compatibility. Type of RAM Frequency: The motherboard will only accept certain frequency of RAM. Voltage: Some RAM will require voltage that is above the regular standard. Make sure that your motherboard can supply that much voltage if required.

Things to be taken care of Timings: lower timings are better as they will reduce latency and increase bandwidth. How much RAM do you need: The more the better. 32bit or 64 bit OS 4 x 1GB or 2 x 2GB sticks

Latest market update DDR4 SDRAM(double data rate fourth generation) is a type of SDRAM with a high bandwidth interface. Released to the market in A higher-speed successor to the DDR2 and DDR3 technologies. Not compatible with any earlier type of RAM. Higher module density and lower voltage requirements, coupled with higher data rate transfer speeds.

Latest market update Theoretically allows for DIMMs of up to 512 GB in capacity. Operates at a voltage of 1.2 V with a frequency between 800 and 1600 MHz. New types of non-volatile RAM, which will preserve data while powered down, are under development

Advances in technology DDR3 SDRAM: Makes further improvements in bandwidth and power consumption in comparison to DDR2. Theoretical peak bandwidths ranging from 6.40 GB/s to 17 GB/s. Zero‐capacitor RAM: Z‐RAM is a denser form of memory, when compared to DRAM. Consumes significantly less power.

Advances in technology Thyristor RAM: Combined strengths of DRAM and SRAM. Has a storage density several times higher than that found in conventional six‐transistor SRAM memory. Magnetoresistive RAM: A non‐volatile computer memory (NVRAM)

Advances in technology Resistive RAM: NVRAM Commonly anticipated as a replacement technology for flash memory Nano‐RAM Phase‐change RAM

The past The first practical form of RAM was the Williams tube starting in Magnetic-core memory was invented in 1947 and developed up until the mid-1970s. Magnetic core memory was displaced by solid-state memory. DRAM was invented in 1968 greatly increasing the memory density. Single Data Rate SDRAM widely used in the 90s.

THE present DDR2 SDRAM: Improvements made in memory bandwidth, clock rates, and voltages. This resulted in notable improvements in overall system performance. DDR3 SDRAM: primarily increased the clock rates possible while reducing the voltages.

The future Future technologies like Z-RAM and T-RAM offer a new approach for dynamic memory cell construction which only need one transistor to store 1-bit data. Work on a principal of Floating Body Effect.

Uses Serves as temporary storage and working space for the operating system and applications Virtual memory RAM disk Shadow RAM

Conclusion The constant need to boost memory performance for increasingly powerful system processors drives the development of advanced RAM technologies. There is an increasing trend of developing non‐volatile random access memory or NVRAM. This is primarily driven by the fact that such memory can be used also to replace the non‐volatile memory technologies that are in use today.