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djplaner

The Electronic Digital Computer - How It Started, How It Works and What It Does - NYTim... - 7 views

www.nytimes.com/...it-works-and-what-it-does.html

digital

shared by djplaner on 27 Feb 16 - No Cached
  • Whether it is solving a differential equation on the motion of charged particles or keeping track of a nuts-and-bolts inventory, the digital computer functions fundamentally as a numerical transformer of coded information. It takes sets of numbers, processes them as directed and provides another number or set of numbers as a result
  • Among the characteristics that make it different are the flexibility with which it can be adapted generally to logical operations, the blinding speed with which it can execute instructions that are stored within its memory, and its built-in capacity to carry out these instructions in sequence automatically and to alter them according to a prescribed plan.
  • Despite its size and complexity, a computer achieves its results by doing a relatively few basic things. It can add two numbers, multiply them, subtract one from the other or divide one by the other. It also can move or rearrange numbers and, among other things, compare two values and then take some pre-determined action in accordance with what it finds.
  • ...7 more annotations...
  • For all its transistor chips, magnetic cores, printed circuits, wires, lights and buttons, the computer must be told what to do and how
    • djplaner
      djplaner on 27 Feb 16
       
      Increasingly there are algorithms that mean that the computer doesn't need to be told what to do. It is capable of learning. For example, in the past computers couldn't drive cars on the road. To do this the computer would have to be told how to do everything - accelerate, turn, how far to turn etc. The new algorithms are such that a computer (actually probably many computers) can drive a car without being told what to do (not a perfect analogy, but hopefully useful)
  • If the data put into the machine are wrong, the machine will give the wrong answer
  • Developing the software is a very expensive enterprise and frequently more troublesome than designing the actual "hardware
  • o specify 60,000 instructions
    • djplaner
      djplaner on 27 Feb 16
       
      Facebook reportedly has at least 62 million lines of code (instructions) to make all of its features work.
  • This requires an input facility that converts any symbols used outside the machine (numerical, alphabetical or otherwise) into the proper internal code used by the machine to represent those symbols. Generally, the internal machine code is based on the two numerical elements 0 and 1
    • djplaner
      djplaner on 27 Feb 16
       
      This applies to any data that an ICT uses - pictures, sound etc. It has to be converted into 0s and 1s (binary digits) that software can then manipulate
  • The 0's and 1's of binary notation represent the information processed by the computer, but they do not appear to the machine in that form. They are embodied in the ups and downs of electrical pulses and the settings of electronic switches inside the machine
  • The computational requirements are handled by the computer’s arithmetic-logic unit. Its physical parts include various registers, comparators, adders, and other "logic circuits."
    • djplaner
      djplaner on 27 Feb 16
       
      This is the bit of the ICT that does the manipulation. Everything you do to manipulate data (e.g. apply Instagram filters) is reduced down to operations that an arithmetic-logic unit (ALU) - or similar - can perform
  • djplaner on 27 Feb 16
     
    An "ancient" (1967) explanation of how a digital computer works - including some history.
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