Classification of computers with examples
Discuss the classification of computers with examples. Also, explain the types of memory in detail.
Computer scan is broadly classified by its speed and computing power.
|1||PC (Personal Computer) or Micro-Computers||It is a single-user computer system having a moderately powerful microprocessor. It is termed as a computer that is equipped microprocessor as its CPU.|
|2||Workstation||It is also a single-user computer system, similar to the personal computer, however, has a more powerful microprocessor.|
|3||Mini-Computer||It is a multi-user computer system, capable of supporting hundreds of users simultaneously.|
|4||Main Frame||It is a multi-user computer system, capable of supporting hundreds of users simultaneously. Software technology is different from minicomputers.|
|5||Super-Computer||It is an extremely fast computer, which can execute hundreds of millions of instructions per second.|
PC (Personal Computer)
A PC can be defined as a small, relatively inexpensive computer designed for an individual user. PCs are based on microprocessor technology that enables manufacturers to put an entire CPU on one chip. Businesses use personal computers for word processing, accounting, desktop publishing, and running spreadsheet and database management applications. At home, the most popular use for personal computers is playing games and surfing the Internet.
Although personal computers are designed as single-user systems, these systems are normally linked together to form a network. In terms of power, nowadays high-end models of the Macintosh and PC offer the same computing power and graphics capability as low-end workstations by Sun Microsystems, Hewlett-Packard, and Dell.
The workstation is a computer used for engineering applications (CAD/CAM), desktop publishing, software development, and other such types of applications that require a moderate amount of computing power and relatively high-quality graphics capabilities.
Workstations generally come with a large, high-resolution graphics screen, a large amount of RAM, inbuilt network support, and a graphical user interface. Most workstations also have mass storage devices such as a disk drive, but a special type of workstation, called diskless workstations, comes without a disk drive.
Common operating systems for workstations are UNIX and Windows NT. Like PC, workstations are also single-user computers like PC but are typically linked together to form a local area network, although they can also be used as stand-alone systems.
It is a midsize multi-processing system capable of supporting up to 250 users simultaneously.
The mainframe is very large in size and is an expensive computer capable of supporting hundreds or even thousands of users simultaneously. Mainframe executes many programs concurrently and supports much simultaneous execution of programs.
Supercomputers are one of the fastest computers currently available. Supercomputers are very expensive and are employed for specialized applications that require an immense amount of mathematical calculations (number-crunching).
For example, weather forecasting, scientific simulations, (animated)graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data (e.g. in petrochemical prospecting).
Types of computer memory
Internal memory, also known as primary memory, stores small amounts of data that the computer can access while you’re actively using it. Internal memory consists of chips connected to the motherboard and needs to be connected directly to the device in order to use it. There are two basic types of internal memory called RAM and ROM, and those have their own subsets of memories.
Random-access memory (RAM) is the primary internal memory of the central processing unit (CPU). Your electronic device uses it for storing temporary data. It does this by providing applications with a place to store data you’re actively using so that they can quickly access the data. The amount of RAM on your device controls its performance and speed. If you don’t have enough RAM, it may process programs slowly which can affect the output and speed with which you can use the computer.
RAM also has “volatile memory” because it loses the data it was storing if you turn off the device. For example, if you’re on your laptop using the internet browser and your computer gets turned off, it may not have saved the web pages you were previously using because RAM only stores that information temporarily.
Dynamic random-access memory (DRAM) is one of the two specific types of RAM seen in modern devices, such as laptops, desktops, portable devices, and gaming systems. It’s the more affordable of the two types of RAM and produces high-capacity memory. It’s made of two components, transistors, and capacitors, which require a recharge every few seconds to retain its data. Like RAM, it also loses data when it loses power and has volatile memory.
Static random access memory (SRAM) is the second type of RAM and stores data as long as there is power in the system, unlike DRAM which is refreshed much more frequently. Because it holds power longer, it’s more expensive than DRAM, which typically makes it not as widely used. Users generally use SRAM for cache memory, which makes it a faster form of memory than DRAM.
Read-only memory (ROM) is another type of primary internal memory, but unlike RAM, ROM is non-volatile and stores data permanently. It does not depend on the device to be turned on in order to save data. Instead, a programmer writes the data into individual cells using binary code, which represents text using the “1” and “0” two-symbol system. Because you cannot alter the data on ROM, you can use this type of memory for aspects that don’t change, such as the boot-up of software or firmware instructions, which help a device function properly.
Programmable read-only memory (PROM) is a type of ROM that begins as memory with no data on it. A user can write data onto the chip using a special device called a PROM programmer. Like ROM, data is permanent once a user has written it onto the chip. This type of memory may be useful to programmers who would like to create specific firmware for a chip and use it to alter the typical function of a system.
Erasable programmable read-only memory (EPROM) is another type of ROM chip that users can write data on as well as erase old data and reprogram it. You can erase the current data by using ultraviolet (UV) light in the form of a quartz crystal window at the top of the chip. After you’ve erased the data, you can use the PROM programmer to reprogram it. You can only erase data from an EPROM chip a certain number of times because excessive erasing can damage the chip and make it unreliable for future use.
Electrically erasable programmable read-only memory (EEPROM) is the final type of non-volatile ROM chip that usually replaces the need for PROM or EPROM chips. This type of memory also allows users to erase and reprogram data onto the chip, but does so using an electric field and is much quicker at erasing data than the EPROM. In addition, you can conveniently erase data while the chip is still inside the computer, whereas EPROM chips need to be taken out of the computer to erase it.
Cache memory is an internal high-speed semiconductor memory that stores instances of data frequently used by the CPU. It provides access to the CPU, so when the CPU requests data or programs the cache memory can transfer them to the CPU almost instantly. Cache memory usually sits between the CPU and RAM serves as a buffer between the two.
External memory, also known as secondary memory, is memory not directly connected to the CPU that you can attach or remove as needed. There are many types of external memory that individuals use in their devices. Examples include external hard drives, flash drives, memory cards, and compact discs (CDs). You can store data from a computer onto external memory, remove it from the device and connect it with another compatible device to transfer data.
- Optical drive
Optical drive memory is an external memory that can both store and read data using light. The most common types are CDs, DVDs, and Blu-ray discs. To access the contents on an optical drive, you place the disc inside the computer and the computer spins the disc. A laser beam inside the system scans it, receives the data on the optical drive, and uploads it onto the computer. This type of memory can be useful because it’s generally inexpensive, easily accessible and stores a lot of data.
- Magnetic storage
Magnetic storage devices have a coating of magnetic material where it encodes data as an electric current. This type of memory uses magnetic fields to magnetize small sections of a metal spinning disk. Each section represents a “1” or a “0” and contains an extensive amount of data, often many terabytes. Users like this type of memory because it’s affordable, durable, and can store a lot of data. Common forms of magnetic storage devices are magnetic tape, hard disk drives, and floppy disks.
- Solid-state drives
Solid-state drives are a form of external memory made up of silicon microchips. They’re similar to magnetic storage devices because you can remove them from the device you’re storing or extracting data from, but solid-state drives are more modern. They’re also faster because the memory keeps the binary data stored electrically in silicon chips known as cells. RAM uses a similar technique, but solid-state drives can keep memory stored even when you turn off a device because they use flash memory. Common types are the universal serial bus (USB) memory stick or USB flash drive.
Virtual memory is another type of secondary memory in the form of a hard drive or solid-state drive that enables a computer to compensate for shortages of physical memory by transferring data from RAM to disk storage. When availability on RAM is running low, virtual memory moves data to a paging file, which is a portion of a hard disk used as an extension of RAM. This is a temporary process that disappears when RAM has more space available.
For example, if a user is on their device and using multiple applications at once, they may use a large portion of available RAM, which could slow down the device and its ability to efficiently operate the programs. The data the computer isn’t using then gets transferred to virtual memory to provide more space for the RAM to run the applications at their full capacity.
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