Memory DRAM Dynamic random access memory Main form

Memory

DRAM Dynamic random access memory � Main form of memory in personal computers and game consuls � Stores each bit of data in a separate capacitor within an integrated circuit �

DRAM Capacitor can be either charged or discharged � Called dynamic memory because if capacitors must be periodically charged � If not charged the information stored in the capacitors will eventually be lost �

DRAM Type of memory used by the CPU � Each chip holds rows and columns of data � A DRAM chip that holds 1, 048, 576 rows and 8 columns would be 1 M x 8 chip � › “M” means megabyte Originally RAM came in one bit wide sticks � Now RAM is available in 32 -bit and 64 -bit sticks �

DRAM Advantages � Structural simplicity › Only one transistor and one capacitor per bit �SRAM has sic transistors � Inexpensive � Small to manufacture in size � Can hold larger amounts of information

DRAM Disadvantages � Loses data when power is removed � Because data needs to be refreshed it is slower than SRAM

SRAM � Static random access memory � Memory is lost once the power is lost � Typically find that SRAM is used in: › › cache memory, hard drive buffers and in other electronics such as children's toys Electronic games

SRAM Advantage � Does not loses data when powered down � Date does not need to be continuously refreshed � Faster then DRAM

SRAM Disadvantage � Expensive to manufacture � Larger than DRAM

SDRAM � Synchronous dynamic random access memory � Because it is synchronous it is tied to the system clock � Allows for higher transfer rates with interfaces possible � Has to wait for a clock signal before it can respond to control inputs and synchronize with the computer

SDRAM � Introduced in 1996 on a dual inline memory module stick (DIMM) � Had varying number of pins � DIMM slots that stored the memory referred to as “banks”

SDRAM Advantages � Allows computers to run at higher mega hertz � Extremely protective of data bits that are stored into the computer › This means it will not allow any corrupt material to be stored in it's drives. � Uses pipelining › that allows more then one command to be accept at one time

SDRAM Disadvantages � Not good at checking to ensure that electrons in the computer system are working properly › This means it needs to be constantly refreshed to ensure that no information is not lost

RAMBUS � Leader in the computer memory industry � Develops and licenses high-performance memory logic and circuit design technology and provides licensees with product design � Created RDRAM

RDRAM Developed for the Pentium 4 by Rambus � Can handle speeds up to 800 MHz � Not well accepted by the industry because of high cost and production delays �

RDRAM � Came in two sizes › 184 -pin (desktops) › 160 -pin (laptops) � Had speed ratings of 600 MHz, 700 MHz, 800 MHz, or 1066 MHz � Had to be installed in pairs because it alternated between two stick to increase speed

RDRAM � All slots on motherboard had to be populated � Roadblocks faced by RDRAM › Technology was owned entirely by Rambus › Expensive › Rambus and Intel made a closed deal and RDRAM only worked on Pentium 4 systems using Intel

DDR SDRAM � Double data rate � Same principle as RDRAM › Doubled speed by making two processes for every clock cycle � Cost only slightly more than regular SDRAM � 184 -pin for desktops � 172 -pin or 200 pin for laptops

DDR SDRAM � Sticks are notched so that the wrong stick can not accidentally be placed in the wrong slot � Eventually became adopted as the standard system RAM � In 2003 Intel ceased producing for RDRAM and adopted SDRAM � Fastest version ran at 4. 8 gigabytes per second

DDR 2 Successor to DDR � Runs faster than DDR by clock-doubling the input/output circuits � Uses less power � Uses 240 -pin DIMM which is not compatible with DDR �

DDR 3 � Newest in line of DDR � More efficient architecture � 30 percent lower power consumption � Uses a 240 -pin DIMM, which is slotted differentially which prevents users from installing the wrong ram � Double the buffer of DDR 2 from 4 to 8 bits

DDR 3 � Extending memory profile (xmp) › Enables RAM to be overclocked � Triple-channel memory › Works like dual channel but uses three sticks instead of two

DDR / DDR 2 / DDR 3 � Double data rate � Neither forwards or backwards compatible � Double data rate means that DDR can achieve nearly twice the bandwidth of a single data rate (SDR) SDRAM running at the same clock frequency, due to this double pumping. DDR 1

DDR 2 Versus DDR 3 � http: //www. youtube. com/watch? v=m. ZAQ 4 Y 0 tjts&feature=related

Single Sided and Double Sided � Single sided have chips on only one side of the sick � Double sided have chips on both sides of the stick � Majority of sticks are single sided � Some motherboards are not compatible with double sided ram

Latency The delays incurred when a computer tries to access data from the stick of RAM � The latency number reflects how many clicks of the system clock it takes before the RAM responds � Sticks with lower latency are “faster” because they have smaller delays � One stick with lower latency may cost far more than a the same stick with a higher latency �

Parity vs. Non-parity � Parity RAM was the first form of error detecting RAM � Uses for computers that must be precise all the time � On occasion there will be an error, parity RAM detects the error

ECC vs. non-ECC � Error correction code � Detects any time a single bit is incorrect � It fixes any errors on the fly � ECC RAM is slower than non-ECC RAM because of the error checking � Non- ECC RAM does not do error checking

Single channel vs. dual channel � Dual channel is faster and allows for more DIMMs � Dual channel means that you have two channels/pathways for your CPU to access your RAM r � Single channel means there is only one channel � More channels allows for more data to be transferred which results in more speed

Installing RAM � http: //www. youtube. com/watch? v=pem. Qxh. E 7 Jhk

Install and configure peripherals and input devices � The following should automatically configure, or only need their attached installed CD to configure › › � If Keyboard Bar code reader Multimedia Mouse will not configure you may need to download a driver

Biometric Authentication � Uses some sort of physical characteristic to identify the user, such as › › Face Eye Fingerprint Handprint � Free face recognition software: › http: //www. youtube. com/watch? v=h. Uc_2 OR 7 z. Q 8

Touch screen �A touch screen allows the user to physically touch the screen to open, close and move through an application � http: //www. youtube. com/watch? v=6 jho. Ws. H w. U 7 w&feature=related

KVM Switch The KVM Switch allows the user to access different computers using a single monitor, keyboard, and mouse. � KVM stands for Keyboard, Video, and Mouse � When installing turn off all computers that will be connected. � Connect all computers to the switch then turn back on the computers. � Windows should recognize the new devices and automatically install them. �

Helpful Links � http: //www. youtube. com/watch? v=E 4 PIDZr. B Gz. Q � http: //www. youtube. com/watch? v=r. Twx. XHswb. E