Module-1-Lesson-2.pdf

Lesson 2 COMPUTER HARDWARE CATEGORIES AND STORAGE DEVICES Introduction Hardware is the physical equipment which includes the input devices, central processing unit, and output devices. The input devices are used to input data into the computer. The central process...

Lesson 2 COMPUTER HARDWARE CATEGORIES AND STORAGE DEVICES Introduction Hardware is the physical equipment which includes the input devices, central processing unit, and output devices. The input devices are used to input data into the computer. The central processing unit or CPU or microprocessor is the brain of the computer, it is stored inside the computer case and placed in a slot within the motherboard together with the other components. The output devices allow the user to see the result of the data that has been processed. Storage devices are used to store data. Storage devices may either be internally installed in the CPU case or removable. Learning Objectives 1. Describe the computer hardware. 2. Identify the input and output devices. 3. Classify different storage devices and their capacity. 4. Evaluate the hierarchy of storage devices and their characteristics. Lecture Discussion Input Devices The most common input devices are the mouse and keyboard. Input devices allow people to interact with a computer. They allow users to input selected data into the computer for processing. Other input devices may include the scanner, which acquires text or graphics by scanning. The web camera is another input device that captures video and images into the computer for storage or for viewing by other people. Joystick and gamepad are input devices for computer gaming. Today, digital and video cameras are also used as input devices. Mouse The mouse acts as the pointing device that you can use to choose programs and files to open, functions to activate, to determine a typing or drawing starting point, function selection, and to scroll pages up or down. Keyboard The keyboard is a computer input device modeled from the keys of a typewriter. It is an arrangement of keys or buttons where characters are printed. The characters consist of letters, numbers or signs, and each one is represented by a specific key. Other special keys or combinations of keys also have a corresponding function. The keyboard allows one to input texts, numbers, special characters, and other functions into the computer. Scanner The image scanner is a computer input device that scans and copies images, objects, texts, and handwriting, and converts them as a digital image. Printed pictures, especially those from the pre- computer home era, can now be scanned, modified, saved, and printed. Web Camera The web camera or webcam is an input device that functions like a digital and video camera. It allows one to place images into the computer. It may be built-in or may be attached to the computer unit. Webcam can be used for video conferencing with friends, relatives, or business associates allowing the participants to see each other. Game Pad The game pad, also called joy pad or control pad functions as handheld game controller for computer games. It has buttons corresponding to some of the fingers which give one better control of the characters being played in a computer game. Joystick The joystick is a computer input device used as a control device that pivots around so that one could move in any direction. It is usually used in video games involving flight control for airplanes and other aircraft. Joystick has also found use in controlling machines such as cranes, unmanned submarines, trucks, and some medical surgical operations. Trackball A variation on the mouse is the trackball. You may have used a trackball to play a video game. The trackball is like an upside-down mouse where you roll the ball directly with your fingers. The popularity of the trackball surged with the advent of laptop computers, when traveling users found themselves without a flat surface on which to roll the traditional mouse. Microphone A microphone is an input device connected to the computer to the sound card via microphone port. The microphone can be use as voice recorder, VoIP, computer gaming, online chatting, and recording of songs and musical instruments. Output Devices The monitor, printer, and the speakers are the most commonly used output devices of most desktop computers. The monitor functions like a television where you can view and see the current encoded data or processed information. The printer allows users to have a hard or printed copy of the desired data or information available inside the computer. Modern microcomputers require speakers to appreciate movies, music, graphic presentation, and even computer alerts. Monitor The monitor is an output device that functions as a visual display unit for images, text, or graphics generated by the computer. The kinds of monitors are the modern, flat panel Liquid Crystal Display (LCD) which occupies less space; and the older and bulkier Cathode Ray Tube (CRT) model. Printer Printer is a computer output device that produces a permanent or hard copy human readable text and /or graphics of documents stored in the computer. There are four (4) kinds of printers:  1. Dot Matrix Printer is a computer printer that prints by hammering or striking an ink-soaked cloth ribbon against a paper. It functions just like the typewriter, and the advantage of this type of printer is that it can easily create carbon copies because of the impact action of the printing process and the cost per page of printing is relatively cheap. 2. LaserJet Printer is a computer printer that produces high-quality prints of text or graphics on plain paper. Color and black and with printing are available in this type of printer. LaserJet printers have faster speeds than dot matrix and inkjet printers. Printing in laser is based on the principle of photocopiers. 3. Inkjet Printer is a computer printer most commonly used at home or in the office. The prices of printers of this kind have significantly gone down and it allows one to print high quality output both in color and in black and white. It can be used in many kinds of mediums, aside from paper. These droplets onto a paper or other media. 4. Plotter is a printing device that operates by moving a set of four pens in different colors over a paper surface and can also have shading features. Most plotters are used in printing computer-aided designs of houses, buildings, mechanical equipment, electrical and electronic designs, landscape and interior designs, maps, bar charts, engineering drawings, and even two- or three-dimensional illustrations. 5. 3D Printing is a process in which a digital model is turned into a tangible, solid, three- dimensional object, usually by laying down many successive, thin layers of a material. 3D printing has become popular so quickly because it makes manufacturing accessible to more people than ever before. Speakers Computer speakers are your audio output for music, video, and computer alerts. They are normally amplified so that one can enjoy the available audio output from the computer. A variety of speakers are available in the market today. Speakers may have the simple two-piece systems, or the three-, four-, five-piece systems with sub-woofer, and surround system. Storage Devices There are many available removable storage devices that are commonly used due to their movability. One can simply bring this data or information in the portable memory and work in another place, as long as there is an available computer with a software that is capable of reading data. 1. Floppy Disk – It is a small capacity magnetic storage device inside a plastic case accessible by a floppy disk drive. It comes in 3 ½ inch size and a capacity of 1.44 MB (Megabyte). Today, few computers have floppy disk drive and few users are using this storage. 2. Optical Disc – Optical media or optical discs are storage media that use laser technology to store data onto a circular plastic or metallic disc. The data in the disc are accessed by the use of an Optical Disk Drive (ODD). a. Compact Disc also commonly known as the CD, is the most widely used optical disc with a standard capacity of around 700 MB (megabytes). There are three (3) types of CD: the CD-ROMs, CDRs and the Rewritable CD.  i. CD-ROMs (Compact Disc-Read Only Memory) are CDs with pre- installed data such as music, movies, and programs. Data or information inside the CD could not be altered and are only available for access or reading. They are read by an optical disk drive or a CD Drive. ii. CD-R or Compact Disk Recordable is a CD where one can store or write data using a CD writer and once written into the CD, it stays there permanently. This CD is also known as the “write once” CD. CDr is used to store data such as music, movies, word processing and spreadsheet files, and other data for future access. iii. CD-RW also known as Re-writable CD, is a CD where in data stored inside can be altered, erased, and then saved again. These are versatile discs since they can be used as temporary storage for work in progress. iv. Blu-ray is a high definition, high capacity data and video storage device. Blue laser is used to read and write to the disk that is why it is called blu- ray. A Blu-Ray Disc can store 25 to 50 GB of data which is between 5 and 10 times compared to a DVD. The use of BD is in high-definition video. b. Digital Versatile Disc (DVD) is better than CDs in terms of capacity, it looks like a CD but has a capacity of 4.7 GB, which is 17 times the capacity of a CD. DVDs can be accessed by the use of a DVD drive; most DVD drives can also read CDs. Like the CDs, DVDs have also DVD-ROM, DVD Recordable, and DVD Rewritable. i. DVD-ROM is DVD-Read Only Memory which is used extensively to distribute movies, since a full length movie can be stored in one DVD. The music and video quality is a lot better compared to CD-ROMs and is comparable to those we view on wide screen theaters. Today’s DVDs are also used to distribute computer programs and music videos. Data stored in the DVD-ROM cannot be changed. It can only be read or played. ii. DVD Recordable has two form formats, the DVD-R and DVD+R; these are competing recording formats for DVD, although recent players and recorders can view and write on both format. Users can only write or record once into the DVD, and data is now permanently stored into the DVD. iii. DVD Rewritable or DVD-Rw is DVD in which stored data can be altered, erased, and re-stored into the DVD. This is a versatile DVD especially “projects in progress” so that future insertions and alterations may be possible. iv. Mini CD and Mini DVD are CDs and DVDs in a smaller size format also known as the 3-inch CDs or DVDs. They function just like the standard CDs and DVDs but of smaller capacity but have the advantage of being small. They also come in CD-ROM, CD-R, and CD-Writable; or DVD-ROM, DVD- R, and DVD-Writable. 3. External DVD Drives – The advent use of smaller and compact mobile computers such as the sub-notebooks and netbooks, which do not have CD or DVD drives, has paved the way in the use of external DVD drives. DVD drives can be connected to the CPU using a USB connector and the Windows program and other operating systems automatically  recognize the drives and can be used immediately. Current external drives can read CDs and DVDs and can write or record data to recordable CDs and DVDs. Hard Disks Almost all personal computers use the hard disk as the main storage where data and programs are saved, retrieved, modified, then stored again for future use. It is directly connected to the motherboard by a data cable. Hard disks are also used in laptop computers but of a smaller size. A hard disk is a non-volatile storage device that is an essential component of computer system hardware, personal desktops, laptops, and even server computers. Non-volatile means stored data and information remain even when the computer power is turned off. The term hard disk was used to differentiate it from the soft floppy disk. The hard disk has significantly a lot of storage space and processes (read and write) data faster. A hard disk has magnetized disks inside, stacked one after another, where data are recorded by magnetizing. Magnetic storage technology has the advantage of being easily erased and written on, and it can remember or store magnetic information for a very long time. A hard disk has a spindle that holds several circular non-magnetic disks called platters, usually made of aluminum or glass. A platter requires a read/write head that flies very close to the plate’s magnetic surface, which functions as the reader and writer of data or information on the magnetized surface. The disk is constantly spinning at high speeds and have to wait for the drive heads to align to the correct position to read or write data. Application and Characteristics of Hard Disks A hard disk provides permanent storage for the operating system, application programs, and data when the computer is turned off. The criteria for looking for a good hard disk are the following: 1. Storage Capacity – A hard disks today have storage capacities starting from 80 gigabytes to a few terabytes. The higher the capacity the better it is because this can store more data and programs without the need for additional storage. 2. Rotation Speed – The platters rotate at very high speed with current hard disk speed rate of 5400 to 7200 revolutions per minute (rpm). The faster the rotations of the hard drive, the better, since this would mean faster seek time and faster data transfer rate. 3. Wiring Connection – Connection of the hard disk to the CPU motherboard is either Integrated Drive Electronics (IDE), also known as Parallel Advanced Technology Attachment (PATA) and the newer Serial Advanced Technology Attachment (SATA) cable. The SATA technology has the advantage of less cable bulk, fast data transfer, and low cost. There are several hard disk manufacturers and selection of the brand to buy will be up to the user. A reliable manufacturer (like Seagate, Western Digital, Maxtor, Toshiba, and ExcelStor) provides warranty, has a good track record of supporting customer concerns, and provides reasonable pricing. Kinds of Hard Disk 1. Internal Hard Disk – The term hard disk is usually associated with non-volatile or permanent storage inside the computer box, also called internal hard disk. It stores the programs and files of the computer. Hard disk gets its power source from the motherboard and is directly connected to the CPU via data cable. 2. External Hard Disk – External hard disks are hard disks with enclosure made of plastic or metal, usually aluminum. The popular size is either the 3.5 inch, used for desktop computers; or the 2.5 inch, used for laptop computer. The 3.5 inch hard disk normally requires external power to operate, whereas the 2.5 inch simply connects to the computer via the USB port without additional external power. External hard disks have capacities of 80 GBB up to 3 TB. It is also used as offline storage for less frequently used files and it is used to transport data from one computer location to another. Flash Memory Flash memory is a non-volatile memory that can be electrically erased and reprogrammed which is used for general purpose storage and data transfer used in cellular phones, digital camera, video cameras, handheld devices, PDAs, video game consoles, and other electronic gadgets. The memory offers low cost, high re-record ability, power-free storage, small form factor, fast data transfer, and rugged environmental specifications. This technology is primarily used in flash drives, memory cards, and solid state drives. Kinds of Flash Memory 1. Flash Drive – USB Flash Drive is a flash memory storage device with a USB connector, having a capacity of 4GB to 128 GB. Flash drives are durable, more reliable in data storage, a lot smaller compared to a floppy disk, have large data capacity, fast, and cheaper in terms of cost per memory space (prices are on the downtrend and storage capacity continuously going up). Flash drives have no moving parts, they are simply connected to the USB ports of the computer and USB ports appear on almost all available PCs and laptop released as of this writing. Flash drives with microUSB connectors are available for use with smartphones, tablets, and computers designed as thin as possible. They have the latest USB connectors which make them faster in terms of file transfer. 2. Solid State Drive (SSD) – Solid State Drive has the same characteristic of a flash drive but it has more memory capacity and is used as an alternative to hard disk drives. It has the advantage of having no moving parts and therefore it is resistant to movements and shock, run silently, have faster access time and can be manufactured in smaller packaging. SSDs are now used to replace hard disk and commonly used in tablets and ultra-thin computers. They are also used as external storage just like the external hard disks called external SSDs. The only deterrent to their wide usage is the price. Although the price has dropped significantly over time, they are still three to four times more expensive than the hard disks. 3. Memory Cards – Memory Cards or Flash Memory Cards are solid-state electronic data storage devices that use flash memory. Flash memory is a non-volatile (does not require  power to maintain the information stored in it) memory that can be electrically erased and reprogrammed. It is classified as a general purpose storage and data transfer used in cellular phone, digital camera, video cameras, handheld devices, PDAs, video game consoles, and other electronic gadgets. The memory offers low cost, high re-record-ability, power-free storage, small form factor, fast data transfer, and rugged environmental specifications. a. Compact Flash (CF) – was first produced in 1994 by SanDisk. It is a flash memory mass storage device mostly used in digital camera that has high memory capacity and reliability. The ruggedness and toughness of this card makes it a better choice by photographers “out in the field”. b. Memory Stick – is another model of the flash memory card manufactured by Sony in 1998 for its wide range of products including digital camera, video camera, cellular phones, PDAs, PSP and other devices. This memory card comes in serval types as follows – Memory Stick PRO, Memory Stick Duo, memory Stick Pro Duo, and memory Stick PRO-HG – all are with the same dimension of 31.0 x 20.0 x 1.6 mm and Memory Stick Micro with a dimension of 15.0 x 12.5 x 1.2 mm. c. MultiMedia Card (MMC) – is a standard flash memory card mostly used in cellular phones introduced by Siemens AG and SanDisk in 1997. This memory card has a dimension of 24 mm x 32 mm x 1.4 mm which is as big as a postage stamp. Variants to this card includes the Reduced Size MultiMedia Card (RS-MMC) which is half the size of the regular MMC, Dual-Voltage MultiMedia Card (DV-MMC) which supports both operation at 1.8V, and 3.3 V which allows the card to run on lower voltage, to reduce power consumption; and then the newer MMCplus and MMCmobile both offers dual voltage and other capabilities. The smallest is the MMCmicro which only has a dimension of 14 mm x 12 mm x 1.1 mm or called the micro size, this version however, is not the same as the MicroSD card. d. Secure Digital (SD) is a flash memory card with a dimension of 24 mm x 32 mm x 2.1 mm. This card was developed by Panasonic, SanDisk and Toshiba in 1999 to be used for digital cameras, mobile phones, PDAs, handheld computers, video game consoles and GPS receivers. High capacity formats of this card are called SDHC (SD High Capacity). However, some older gadgets cannot read the SDHC which often requires a SDHC firmware generally not found in older devices. e. MiniSD Card is a card for use with cellphones, digital cameras and MP3 players. Released by SanDisk in 2003, it has a small form factor and a dimension of 21.5 x 20 x 1.4 mm. these cards can be used in gadgets that use SD cards by using an adaptor. MiniSDHC is also available. f. MicroSD is the smallest removable flash memory in the market almost the size of a fingernail at 15 x 11 x 0.7 mm designed for use in cellular phones. MicroSDHC is also available. MicroSD often includes an adaptor so it can be used in gadgets using SD but not on MiniSD. Storage Capacity Data in a digital computer system is represented in binary digits called bits or 0s and 1s in a binary numeral system. All data and information (text, images, and video) in a binary system are represented and stored as a string of bits. Computers only understand binary digit and inside the computer, data is represented as 0 or 1, or strings of 0x and 1s. Each character of the alphabet and the numbers is represented by a byte. A byte is a unit of information that is equal to 8 bits. For example, letter ‘A’ is represented by 00000001. Other letters and numbers have their corresponding 8 bits of 0s and 1s. Computer Storage Capacity Usage Storage Capacity Approximate and exact number of bytes Kilobyte KB 1 thousand 1,024 Megabyte MB 1 million 1,048,576 Gigabyte GB 1 billion 1,073,741,824 Terabyte TB 1 trillion 1,099,511,627,776 Petabyte PB 1 quadrillion 1,125,899,906,842,624 Exabyte EB 1 quintillion 1,152,921,504,606,846,976 Zettabyte ZB 1 sextillion 1,180,591,620,717,411,303,424 Yottabyte YB 1 septillion 1,208,925,819,614,629,174,706,176 Hierarchy of Storage 1. Primary Storage This refers to the memory devices that are directly connected and accessible to the CPU. it helps in the proper operation of the computer system by providing and storing the data and instructions continuously as required. The memories include here are the registers and cache memories inside the CPU chip, and the Random Access Memory (RAM) that is connected to the CPU by a memory bus. Data stored here are lost when power is shut down. The access time using primary is measured in billionth of a second or nanosecond. 2. Secondary Storage This refers to the storage that is not directly accessible by the CPU. The most common secondary storage is the hard disk inside the CPU. The secondary storage like the hard disk is non-volatile which means that it does not lose its data when the power is shut down. Data inside the secondary storage is accessed by the CPU using its input and output channels and is transferred to the primary memory for processing. Access time for the secondary storage is measured in a few thousandths of a second or milliseconds. 3. Tertiary Storage refers to the storage used for huge volumes of data that are stored for future use. These data are archived and are seldom used. Access style may take longer such as a few seconds. Their storage style is not used for home applications but for institutions like a vast electronic library. 4. Off-line Storage This refers to the memories that are not directly connected or controlled by the computer system. The data is stored in the secondary storage device. It can be disconnected and then transported to another location and then used in another computer system. Examples of this type of storage are USB flash drives, memory cards, optical disks, and external hard disks. Storage Characteristics 1. Performance a. Throughput – is measure of data transfer from storage to and from the computer system, usually measured in bytes per second. Today's volume of data transfers are in the range of megabytes per second (Mbps). The higher value is preferable. b. Latency - is the measure of time delayed obtaining the data from a storage location. Today's typical latency is measured in nanoseconds for primary milliseconds for secondary memory, and seconds for tertiary storage. A small value for latency is desirable, since it would mean less data access delay. c. Capacity - is the measure of the amount of information that can be stored in a memory or storage device. Today's RAMs are in the range of 1 gigabyte up to 4 gigabytes. For the secondary storage, such as the hard disk, it ranges from 80 gigabytes up to one terabyte. A higher value is desirable. 2. Accessibility a. Random Access - indicates that data can be accessed within the storage at almost the same time, wherever is the location of the information. This random characteristic is ideal for primary and secondary storage. b. Sequential - Indicates that data is accessed one after another. Data placed first will be accessed in the shortest time, and those stored last will take a longer time to get. Examples of this type of storage are the magnetic cassette tapes used in cassettes and videotapes. 3. Volatility a. Volatile - Data stored here are lost when power is turned off. But usually, memories of this type have small latency values and fast operating speeds. Majority of RAMs are volatile. b. Non-volatile - Data stored here are retained even when power is turned off. Hard disks, floppy disks, optical disks, and flash drives are non-volatile storage media. They are used as secondary and offline storage applications to transfer information from one location to another. Solid State Drive (SSD) Solid-state drives do not have moving parts because they do not rely on spinning platters. Instead, data are pulled in an array of NAND flash. NAND Is a type of logic gate made of transistors that are designed to retain its memory even when there is no power, making it a non-volatile memory just like the hard disk. One SSD may contain thousands or millions of transistors. SSDs are solid devices and store digital data of zeros and ones. One cell of NAND flash may contain two transistors: one of which is the control gate and the other is called the floating gate. Play applying precise voltages to the transistors, it will give a unique pattern of zeros and ones. Advantages of SSD over HDD 1. Faster boot-up time of 20 seconds versus 40 seconds.  2. Faster data read or write speed of 200 to 1500 megabytes per second versus 50 to 200 megabytes per second. 3. Faster opening of application programs. 4 seconds versus 14 seconds. 4. Low noise since there are no moving parts. 5. No need for cooling and can tolerate a wide range of temperatures. The lifespan of a hard disk shortens if operated at temperatures above 35°C. 6. Can operate in temperatures below freezing point up to -55°C, whereas HD can operate at 0°C. 7. Resistant to shock and vibration. 8. Not sensitive to mounting or installation. 9. Very small and lightweight. 10. Consume less power, which could contribute to longer battery life for laptops. Disadvantages of SSD 1. As of this writing, SSD continues to decline in cost, but it is still four times more expensive than a hard disk of the same capacity. 2. NAND flash in SSD has an affinity number of times that you can write on it through the read Does not contribute to the decay process, limiting their usefulness. Manufacturers of SSDs use wear leveling to slow down the degradation of NAND flash by distributing evenly the data written on the SSD memory block. Still, the SDDs decay overtime. Today's computer techies and data centers use a combination of SSD and HDD for their data storage to ensure data protection. They use SSDs for their computers for their obvious advantages of speed and low power, and backup their data to an external hard disk for its reliability and low cost. SSDs and memory cards both use flash memory technology. However, SSDs were designed to be used in a computer system with the intention of replacing the hard disk drives. They were initially shaped just like hard disk drives. But got smaller and smaller as new versions came to. They were designed to be installed on a computer, but unlike memory cards, they were developed for digital cameras, smartphones, and gaming devices. SSD therefore are faster, designed to read or write more times, and sturdier than a typical memory card. External SSDs are now available and have already reached 16 terabytes(TB) in capacity, but are still quite expensive. Random Access Memory (RAM) Random Access Memory or RAM is a computer memory that connects directly to the CPU. It is called random access because it can directly access any data within. RAM is a volatile storage since it loses its contents when the computer power is turned off. There are two types of RAM which differ in terms of technology used, DRAM and SRAM. 1. Dynamic Random Access memory (DRAM) It is the simpler and more popular technology between the two types. Simple, but because internally the electronic circuitry has fewer components, hence makers are able to include more memory space into it, making it cheaper to manufacture. This technology is common because this is the type that is installed in most desktop or laptop computers. DRAM formed the larger RAM in the computer. The disadvantage of DRAM is the need to refresh it, which is done automatically within the computer system. Because of this refresh necessity, it takes a longer time to access the data within it. If the data is not refreshed, the data will be lost since DRAMs are like water drums with small holes where data slowly drains and will eventually lose its contents if it is not refilled. This leaking character is due to one of the components inside called the capacitor. a. SDRAM – Synchronous DRAM is the present standard RAM for N 6/7new personal computers. This RAM runs at a high clock speed and is synchronized with the CPU's bus frequency. For example, a PC400 SD RAM has a front-side bus frequency of 400 megahertz (MHz). This type of RAM being synchronized with the CPU can accomplish a pattern of operation such as pipelining. Pipelining means in one machine cycle the CPU can accept new instructions before it has finished processing the previous. Processing is faster as compared to a non-pipeline system since the CPU can process more than one operation in one cycle. SD RAM technology for RAM has evolved and has developed the following generations of SDRAMS: i. SDR SDRAM – Single Data Rate SDRAM use 168 DIMMs and operates in the clock rates of 66, 100, and 133 MHz This SDRAM is slower than the later DDR since it can only accept one command and transfers one word of data per clock cycle. ii. DDR SDRAM - Double Data Rate SDRAM 184 pin DIMMs are operating in the clock rates of 133, 166, and 200 megahertz. They are called DDR266, DDR333 and DDR40. These RAMs operate at 2.5 volts. iii. DDR2 SDRAM - is the next generation of DDR SDRAM. It has 240 pins and operates in the clock rates of 200, 266, and 400 megahertz. They are called DDR2- 400. DDR2-533, DDR2-667 and DDR2-800. These RAMs doubles the read and write to four consecutive words and they operate at higher clock frequencies, making them faster and more robust than DDR SDRAM. This RAM was released in 2003. It is operating at 1.8 volts which means DDR2 consumes less power than DDR. It is not compatible which means that you cannot put DDR2 in the place of a DDR RAM. iv. DDR3 SDRAM - it's the next generation of DDR SDRAM which are commercially available in the mid-2007. These RAM doubles the read and write of DDR2 at 8 words per read and write operation. It uses 240 pin and is normally operating in 400, 533, 667, and 800 megahertz called DDR3-800, DDR3-1066, DDR3-1333, and DDR3-1600 respectively. This RAM operates at 1.5 volts, meaning this consumes less power than DDR2 and DDR, thereby extending battery life. DDR, DDR2, and DDR3 are not compatible and are not interchangeable because they operate at. Different voltages. This incompatibility means also there is a different motherboard required for each RAM. Compatibilities occur only on the same DDR number level, meaning one DDR 2 is most likely compatible with another DDR2 operating on a different frequency. v. DDR4 SDRAM - It is the latest generation of SD RAM which was released in the second quarter of 2014. It operates at 1.2 volts and will have more than 2 billion  data transfers per second. This memory uses less power and can handle more data compared to its predecessors–DDR2 and DDR3–which enabled developers to make powerful processors and more capable devices. DDR4 RAMs are not compatible with DDR2 and DDR3 due to their signaling voltage and physical interface. The lower voltage for DDR4 allows for increased battery life for laptops. vi. DDR5 SDRAM - It was released on July 14, 2020, as the successor to DDR4. DDR5 introduced a new feature called DFE (Decision Feedback Equalization) which allows the speed of I/O (input/output) to be scaled, increasing memory bandwidth and improving general performance. DDR5 has clock speeds that range from 2000 to 4000 MHz and range in storage capacity from 64 to 512 GB per DIMM (Dual In- line Memory Module). DDR5 is also more efficient at 1.1 volts compared to DDr4's 1.2 V consumption. These memory chips can only be installed on a motherboard that supports DDR5 memory and is not backward compatible with DDR4 memory slots. Latency is a measure of time delay in a system, also referred to as the access time. In the case of SDRAM, this is the delay encountered when the computer tries to access and read data from the RAM. It is measured. Memory bus plug cycle. Today, the latency is in the range of two nanoseconds for DDR2, 1 nanosecond for DDR3, and less than one nanosecond for DDR4 and DDR5. Generally, the CPU operates faster than the current SRAM and has to wait for the data for a long time. Therefore, lowering the latency of the RAM is important since this will affect the overall performance of the computer. 2. Static Random Access Memory (SRAM) static random access memory (SRAM) has a more complex circuitry than DRAMs. The main advantage of this RAM is that there is no need to refresh it to retain the data. This is the reason why SRAM is faster than the DRAM. But this is still a volatile storage. The complex circuitry, however, makes this RAM more expensive and the memory capacity is not as large as DRAM. As RAM is mainly used in applications requiring speed but less memory, such as registers and cache found inside the microprocessor chip. SRAM's are also found in printers, hard disks, LCD monitors, and routers as memory buffers. Memory buffers, in the case of LCDs and printers, static RAMs are used to hold the image before it is finally displayed or printed. Types of SRAM a. Asynchronous SRAM - This is independent of the timing or clock frequency. This RAM functions using address transition. b. Synchronous SRAM - This is in step with the clock timing. The clock is timed by the rising and falling of a clock signal. The SRAM functions are controlled by the clock signal.