Text, numbers, pictures, audio, and nearly any other form of information can be converted into a string of bits, or binary digits, each of which has a value of 0 or 1. Most modern computers are von Neumann machines.ĭata organization and representation Ī modern digital computer represents data using the binary numeral system. : 20 Such computers are more versatile in that they do not need to have their hardware reconfigured for each new program, but can simply be reprogrammed with new in-memory instructions they also tend to be simpler to design, in that a relatively simple processor may keep state between successive computations to build up complex procedural results. Von Neumann machines differ in having a memory in which they store their operating instructions and data. This is acceptable for devices such as desk calculators, digital signal processors, and other specialized devices. It would have to be reconfigured to change its behavior. Without a significant amount of memory, a computer would merely be able to perform fixed operations and immediately output the result. The former controls the flow of data between the CPU and memory, while the latter performs arithmetic and logical operations on data. This distinction was extended in the Von Neumann architecture, where the CPU consists of two main parts: The control unit and the arithmetic logic unit (ALU). Generally, the fast technologies are referred to as 'memory', while slower persistent technologies are referred to as 'storage'.Įven the first computer designs, Charles Babbage's Analytical Engine and Percy Ludgate's Analytical Machine, clearly distinguished between processing and memory (Babbage stored numbers as rotations of gears, while Ludgate stored numbers as displacements of rods in shuttles). In practice, almost all computers use a storage hierarchy, : 468–473 which puts fast but expensive and small storage options close to the CPU and slower but less expensive and larger options further away. The central processing unit (CPU) of a computer is what manipulates data by performing computations. It is a core function and fundamental component of computers. Read/Write DVD drive with cradle for media extendedĬomputer data storage is a technology consisting of computer components and recording media that are used to retain digital data. When used within a robotic tape library, it is classified as tertiary storage instead. 160 GB SDLT tape cartridge, an example of off-line storage. When connected to a computer it serves as secondary storage. 15 GB PATA hard disk drive (HDD) from 1999. For broader coverage of this topic, see Data storage.

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