Computer Memory: Types, Characteristics, and Functions, Exercises of Computer Fundamentals

Download Computer Memory: Types, Characteristics, and Functions and more Exercises Computer Fundamentals in PDF only on Docsity! What is Computer Memory? Computer memory is just like the human brain. It is used to store data/information and instructions. It is a data storage unit or a data storage device where data is to be processed and instructions required for processing are stored. It can store both the input and output can be stored here. Characteristics of Computer Memory:- *It is faster computer memory as compared to secondary memory. *It is semiconductor memories. *It is usually a volatile memory, and main memory of the computer. *A computer system cannot run without primary memory. How Does Computer Memory Work? When you open a program, it is loaded from secondary memory into primary memory. Because there are various types of memory and storage, an example would be moving a program from a solid-state drive (SSD) to RAM. Because primary storage is accessed more quickly, the opened software can connect with the computer’s processor more quickly. The primary memory is readily accessible from temporary memory slots or other storage sites. Memory is volatile, which means that data is only kept temporarily in memory. Data saved in volatile memory is automatically destroyed when a computing device is turned off. When you save a file, it is sent to secondary memory for storage. There are various kinds of memory accessible. It’s operation will depend upon the type of primary memory used. but normally, semiconductor-based memory is more related with memory. Semiconductor memory made up of IC (integrated circuits) with silicon-based metal- oxide-semiconductor (MOS) transistors. Types of Computer Memory:- In general, computer memory is of three types: 1.Primary memory 2.Secondary memory 3.Cache memory Now we discuss each type of memory one by one in detail: 1. Primary Memory:- It is also known as the main memory of the computer system. It is used to store data and programs or instructions during computer operations. It uses semiconductor technology and hence is commonly called semiconductor memory. Primary memory is of two types: RAM (Random Access Memory): It is a volatile memory. Volatile memory stores information based on the power supply. If the power supply fails/ interrupted/stopped, all the data and information on this memory will be lost. RAM is used for booting up or start the computer. It temporarily stores programs/data which has to be executed by the processor. RAM is of two types: *S RAM (Static RAM): S RAM uses transistors and the circuits of this memory are capable of retaining their state as long as the power is applied. This memory consists of the number of flip flops with each flip flop storing 1 bit. It has less access time and hence, it is faster. Characteristics of Static RAM  Static RAM is much faster than DRAM.  Static RAM has greater storage than DRAM.  Static RAM takes less power to perform. Advantages of Static RAM  Static RAM has low power consumption.  Static RAM has faster access speeds than DRAM.  Static RAM helps in creating a speed-sensitive cache. Disadvantages of Static RAM  Static RAM has less memory capacity.  Static RAM has high costs of manufacturing than DRAM.  Static Ram comprises of more complex design. *D RAM (Dynamic RAM): D RAM uses capacitors and transistors and stores the data as a charge on the capacitors. They contain thousands of memory cells. It needs refreshing of charge on capacitor after a few milliseconds. This memory is slower than S RAM. Characteristics of Dynamic RAM  Dynamic RAM is slower in comparison to SRAM.  Dynamic RAM is less costly than SRAM.  Dynamic RAM has high power consumption. that can be programmed for a piece of specific information. The information stored in the ROM in binary format. It is also known as permanent memory. ROM is of four types: Types of ROM: 1) Masked Read Only Memory (MROM): It is the oldest type of read only memory (ROM). It has become obsolete so it is not used anywhere in today's world. It is a hardware memory device in which programs and instructions are stored at the time of manufacturing by the manufacturer. So it is programmed during the manufacturing process and can't be modified, reprogrammed, or erased later. The MROM chips are made of integrated circuits. Chips send a current through a particular input- output pathway determined by the location of fuses among the rows and columns on the chip. The current has to pass along a fuse-enabled path, so it can return only via the output the manufacturer chooses. This is the reason the rewriting and any other modification is not impossible in this memory. 2) Programmable Read Only Memory (PROM): PROM is a blank version of ROM. It is manufactured as blank memory and programmed after manufacturing. We can say that it is kept blank at the time of manufacturing. You can purchase and then program it once using a special tool called a programmer. In the chip, the current travels through all possible pathways. The programmer can choose one particular path for the current by burning unwanted fuses by sending a high voltage through them. The user has the opportunity to program it or to add data and instructions as per his requirement. Due to this reason, it is also known as the user-programmed ROM as a user can program it. To write data onto a PROM chip; a device called PROM programmer or PROM burner is used. The process or programming a PROM is known as burning the PROM. Once it is programmed, the data cannot be modified later, so it is also called as one-time programmable device. Uses: It is used in cell phones, video game consoles, medical devices, RFID tags, and more. 3) Erasable and Programmable Read Only Memory (EPROM): EPROM is a type of ROM that can be reprogramed and erased many times. The method to erase the data is very different; it comes with a quartz window through which a specific frequency of ultraviolet light is passed for around 40 minutes to erase the data. So, it retains its content until it is exposed to the ultraviolet light. You need a special device called a PROM programmer or PROM burner to reprogram the EPROM. Uses: It is used in some micro-controllers to store program, e.g., some versions of Intel 8048 and the Freescale 68HC11. 4) Electrically Erasable and Programmable Read Only Memory (EEPROM): ROM is a type of read only memory that can be erased and reprogrammed repeatedly, up to 10000 times. It is also known as Flash EEPROM as it is similar to flash memory. It is erased and Difference Random Access Memory (RAM) Read Only Memory (ROM) Cost RAM is more costlier than ROM. ROM is cheaper than RAM. Chip Size A RAM chip can store only a few gigabytes (GB) of data. A ROM chip can store multiple megabytes (MB) of data. Function Used for the temporary storage of data currently being processed by the CPU. Used to store firmware, BIOS, and other data that needs to be retained. Secondary Memory We have read so far, that primary memory is volatile and has limited capacity. So, it is important to have another form of memory that has a larger storage capacity and from which data and programs are not lost when the computer is turned off. Such a type of memory is called secondary memory. In secondary memory, programs and data are stored. It is also called auxiliary memory. It is different from primary memory as it is not directly accessible through the CPU and is non-volatile. Secondary or external storage devices have a much larger storage capacity and the cost of secondary memory is less as compared to primary memory. Use of Secondary memory Secondary memory is used for different purposes but the main purposes of using secondary memory are:  Permanent storage: As we know that primary memory stores data only when the power supply is on, it loses data when the power is off. So we need a secondary memory to stores data permanently even if the power supply is off.  Large Storage: Secondary memory provides large storage space so that we can store large data like videos, images, audios, files, etc permanently.  Portable: Some secondary devices are removable. So, we can easily store or transfer data from one computer or device to another. Types of Secondary memory Secondary memory is of two types: 1. Fixed storage In secondary memory, a fixed storage is an internal media device that is used to store data in a computer system. Fixed storage is generally known as fixed disk drives or hard drives. Generally, the data of the computer system is stored in a built-in fixed storage device. Fixed storage does not mean that you can not remove them from the computer system, you can remove the fixed storage device for repairing, for the upgrade, or for maintenance, etc. with the help of an expert or engineer. Types of fixed storage: Following are the types of fixed storage:  Internal flash memory (rare)  SSD (solid-state disk)  Hard disk drives (HDD) 2. Removable storage In secondary memory, removable storage is an external media device that is used to store data in a computer system. Removable storage is generally known as disks drives or external drives. It is a storage device that can be inserted or removed from the computer according to our requirements. We can easily remove them from the computer system while the computer system is running. Removable storage devices are portable so we can easily transfer data from one computer to another. Also, removable storage devices provide the fast data transfer rates associated with storage area networks (SANs). Types of Removable Storage:  Optical discs (like CDs, DVDs, Blu-ray discs, etc.)  Memory cards  Floppy disks  Magnetic tapes  Disk packs  Paper storage (like punched tapes, punched cards, etc.) Secondary memory devices Following are the commonly used secondary memory devices are: 1. Floppy Disk: A floppy disk consists of a magnetic disc in a square plastic case. It is used to store data and to transfer data from one device to another device. Floppy disks are available in two sizes (a) Size: 3.5 inches, the Storage capacity of 1.44 MB (b) Size: 5.25 inches, the Storage capacity of 1.2 MB. To use a floppy disk, our computer needs to have a floppy disk drive. This storage device becomes obsolete now and has been replaced by CDs, DVDs, and flash drives. 2. Compact Disc: A Compact Disc (CD) is a commonly used secondary storage device. It contains tracks and sectors on its surface. Its shape is circular and is made up of polycarbonate plastic. The storage capacity of CD is up to 700 MB of data. A CD may also be called a CD-ROM (Compact Disc Read-Only Memory), in this computers can read the data present in a CD-ROM, but cannot write new data onto it. For a CD-ROM, we require a CD-ROM. CD is of two types:  CD-R (compact disc recordable): Once the data has been written onto it cannot be erased, it can only be read.  CD-RW (compact disc rewritable): It is a special type of CD in which data can be erased and rewritten as many times as we want. It is also called an erasable CD. 3. Digital Versatile Disc: A Digital Versatile Disc also known as DVD it is looks just like a CD, but the storage capacity is greater compared to CD, it stores up to 4.7 GB of data. DVD-ROM drive is needed to use DVD on a computer. The video files, like movies or video recordings, etc., are generally stored on DVD and you can run DVD using the DVD player. DVD is of three types:  DVD-ROM(Digital Versatile Disc Readonly): In DVD-ROM the manufacturer writes the data in it and the user can only read that data, cannot write new data in it. For example movie DVD, movie DVD is already written by the manufacturer we can only watch the movie but we cannot write new data into it.  DVD-R(Digital Versatile Disc Recordable): In DVD-R you can write the data but only one time. Once the data has been written onto it cannot be erased, it can only be read.  DVD-RW(Digital Versatile Disc Rewritable and Erasable): It is a special type of DVD in which data can be erased and rewritten as many times as we want. It is also called an erasable DVD. 4. Blu-ray Disc: A Blu-ray disc looks just like a CD or a DVD but it can store data or information up to 25 GB data. If you want to use a Blu-ray disc, you need a Blu-ray reader. The name Blu-ray is derived from the technology that is used to read the disc ‘Blu’ from the blue-violet laser and ‘ray’ from an optical ray.