HARDWARE

Random-access memory (RAM) is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in bursts, although the name DRAM / RAM has stuck. However, many types of SRAM, ROM, OTP, and NOR flash are still random access even in a strict sense. RAM is often associated with volatile types of memory (such as DRAM memory modules), where its stored information is lost if the power is removed. Many other types of non-volatile memory are RAM as well, including most types of ROM and a type of flash memory called NOR-Flash. The first RAM modules to come into the market were created in 1951 and were sold until the late 1960s and early 1970s.

Other memory devices (magnetic tapes, disks) can access the storage data only in a predetermined order, because of mechanical design limitations.

Types of RAM

The two main forms of modern RAM are static RAM (SRAM) and dynamic RAM (DRAM). In static RAM, a bit of data is stored using the state of a flip-flop. This form of RAM is more expensive to produce, but is generally faster and requires less power than DRAM and, in modern computers, is often used as cache memory for the CPU. DRAM stores a bit of data using a transistor and capacitor pair, which together comprise a memory cell. The capacitor holds a high or low charge (1 or 0, respectively), and the transistor acts as a switch that lets the control circuitry on the chip read the capacitor's state of charge or change it. As this form of memory is less expensive to produce than static RAM, it is the predominant form of computer memory used in modern computers.

Both static and dynamic RAM are considered volatile, as their state is lost or reset when power is removed from the system. By contrast, Read-only memory (ROM) stores data by permanently enabling or disabling selected transistors, such that the memory cannot be altered. Writeable variants of ROM (such as EEPROM and flash memory) share properties of both ROM and RAM, enabling data to persist without power and to be updated without requiring special equipment. These persistent forms of semiconductor ROM include USB flash drives, memory cards for cameras and portable devices, etc. As of 2007, NAND flash has begun to replace older forms of persistent storage, such as magnetic disks and tapes, while NOR flash is being used in place of ROM in netbooks and rugged computers, since it is capable of true random access, allowing direct code execution.

ECC memory (which can be either SRAM or DRAM) includes special circuitry to detect and/or correct random faults (memory errors) in the stored data, using parity bits or error correction code.

In general, the term RAM refers solely to solid-state memory devices (either DRAM or SRAM), and more specifically the main memory in most computers. In optical storage, the term DVD-RAM is somewhat of a misnomer since, like CD-RW, a rewriteable DVD must be erased before it can be rewritten.

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Serial ATA Nedir?

Serial ATA, masaüstü bilgisayarlardaki, bazı sunuculardaki ve ağa bağlı depolama cihazlarındaki paralel ATA fiziksel depolama arabiriminin evrimleşmiş hali olarak düşünülebilir.

Spesifikasyon daha ince, daha esnek kabloların ve daha az iğne sayılarının kullanılmasına olanak veriyor. Bu dabilgisayar üreticilerinin sistemlerini yönlendirmesi ve kurulması kolay kablolarla tasarlamalarını sağlıyor. Bununla birlikte şu an kullanılan Paralel ATA teknolojisinden daha kolay, daha esnek anakart yönlendirmesini de olası kılıyor.

Serial ATA II ile daha da geliştirilecek olan teknoloji önümüzdeki yılların bilgisayarlarının ihtiyaç duyduğu depolama arabirimlerini sağlamaya aday.Serial ATA Çalışma Grubu şu anda silikon tasarımı, kablo/konektör, depolama gibi konularda dünya lideri olan 80'den fazla üye ile oldukça güçlü bir konumda bulunuyor.

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In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons. It sometimes features other elements, such as "wheels", which allow the user to perform various system-dependent operations, or extra buttons or features that can add more control or dimensional input. The mouse's motion typically translates into the motion of a cursor on a display, which allows for fine control of a graphical user interface.

Optical and laser mice

Optical mice make use of one or more light-emitting diodes (LEDs) and an imaging array of photodiodes to detect movement relative to the underlying surface, rather than internal moving parts as does a mechanical mouse. A laser mouse is an optical mouse that uses coherent (laser) light.

Inertial and gyroscopic mice

Often called "air mice" since they do not require a surface to operate, inertial mice use a tuning fork or other accelerometer (US Patent 4787051) to detect rotary movement for every axis supported. The most common models (manufactured by Logitech and Gyration) work using 2 degrees of rotational freedom and are insensitive to spatial translation. The user requires only small wrist rotations to move the cursor, reducing user fatigue or "gorilla arm". Usually cordless, they often have a switch to deactivate the movement circuitry between use, allowing the user freedom of movement without affecting the cursor position. A patent for an inertial mouse claims that such mice consume less power than optically based mice, and offer increased sensitivity, reduced weight and increased ease-of-use. In combination with a wireless keyboard an inertial mouse can offer alternative ergonomic arrangements which do not require a flat work surface, potentially alleviating some types of repetitive motion injuries related to workstation posture.

3D mice

Also known as bats, flying mice, or wands, these devices generally function through ultrasound and provide at least three degrees of freedom. Probably the best known example would be 3DConnexion/Logitech's SpaceMouse from the early 1990s.

In the late 1990s Kantek introduced the 3D RingMouse. This wireless mouse was worn on a ring around a finger, which enabled the thumb to access three buttons. The mouse was tracked in three dimensions by a base station. Despite a certain appeal, it was finally discontinued because it did not provide sufficient resolution.

A recent consumer 3D pointing device is the Wii Remote. While primarily a motion-sensing device (that is, it can determine its orientation and direction of movement), Wii Remote can also detect its spatial position by comparing the distance and position of the lights from the IR emitter using its integrated IR camera (since the nunchuk accessory lacks a camera, it can only tell its current heading and orientation). The obvious drawback to this approach is that it can only produce spatial coordinates while its camera can see the sensor bar.

A mouse-related controller called the SpaceBall™ has a ball placed above the work surface that can easily be gripped. With spring-loaded centering, it sends both translational as well as angular displacements on all six axes, in both directions for each.

In November 2010 a German Company called Axsotic introduced a new concept of 3D mouse called 3D Spheric Mouse. This new concepts of a true 6 DOF input-device uses a ball to rotate in 3 axes without any limitations.

Tactile mice

In 2000, Logitech introduced the "tactile mouse", which contained a small actuator that made the mouse vibrate. Such a mouse can augment user-interfaces with haptic feedback, such as giving feedback when crossing a window boundary. To surf by touch requires the user to be able to feel depth or hardness; this ability was realized with the first electrorheological tactile mice but never marketed.

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Moore's law initially formulated by Gordon Moore, then Chairman of Intel, first appeared in a 1965 article in the 35th anniversary edition of Electronics, "Cramming more components onto integrated circuits." Moore's Law asserts that the complexity of minimum-cost semiconductor components has doubled regularly each year since the first prototype microchip was introduced in 1959.

Throughout the 80s and 90s, Moore's Law began to be rephrased by others in terms of the number of transistors that fit on a chip of fixed size, or the computational power per unit cost. This remarkable law has held strong at least up to the writing of this article, in 2005. In addition, a number of Moore's Law-type variants of exponential growth have appeared in the development of LED lights, resolution of brain scanning devices, mass use of inventions, number of genomes sequenced, availability of RAM, size of magnetic data storage, and fastest possible data transmission speed.

What makes the success of Moore's Law all the more fascinating is that Moore only had 6 years experience with microchips as a basis for his assertion, but nonetheless it has held for 40 additional years. The death of Moore's Law has been predicted multiple times, but it has kept chugging on. Industry experts expect a hiccup in Moore's Law around 2015, when conventional photolithographical techniques will reach their final limits.

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The logic board is a circuit board in an Apple Macintosh computer; in other brands of computers it is known as a motherboard. The logic board houses the crucial components of the computer system and provides connectivity for peripheral devices.

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The parallel port is found on the back of IBM compatible computers and is a 25-pin (type DB-25) computer interface commonly used to connect printers to the computer. Below is an example of the DB25 interface found on the back of the computer.

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