While the technologies employed in digital computers have changed a lot since the first models appeared in the 40s, most still use the von Neumann architecture, published in the early 1940s by John von Neumann, that other authors attributed to John Presper Eckert and John William Mauchly.
Von Neumann architecture describes a computer with 4 main sections: the arithmetic logic unit (ALU stands for the English: Arithmetic Logic Unit), the control unit, main memory, and input devices and output (I / S ). These parts are interconnected by channels called buses drivers:
The memory is a sequence of numbered storage cells, where each bit is a unit of information. The instruction is the information needed to perform what you want with the computer. The celdas ” containing data needed to carry out the instructions in the computer. The number of cells vary widely from computer to computer, and the technologies used for memory have changed considerably, ranging from electromechanical relays, tubes filled with mercury in which acoustic pulses were formed, matrices of permanent magnets, a single transistor circuits integrated with millions of cells on a single chip. In general, memory can be rewritten several million times (RAM) is more like a slate gravestone that memory (ROM) that can only be written once.
The processor (also called central processing unit or CPU) consists of:
A typical schematic symbol for an ALU A and B are operands R is the output, F is the input of the control unit, D is a state of the output
The arithmetic logic unit or ALU is a device designed and built to perform basic operations such as arithmetic operations (addition, subtraction, …), logical operations (AND, OR, NOT), and for comparison or relational. This unit is where does all the computational work.
The unit continues to control the direction of the positions in memory that contain the instructions that the computer will perform at that time, making information retrieval for the ALU operation to be developed. Then transfers the result to appropriate locations in memory. Once this occurs, the control unit goes to the next instruction (typically located at the following location, unless the instruction is a jump instruction informing the computer that the next instruction will be located in another position in the memory).
Devices E / S used the computer to obtain information from the outside world and / or communicate the results generated by the computer to the outside. There is a very wide range of devices E / S as keyboards, monitors, disk drives or flexible webcams.


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