Cph

Computer History

By tnishimwe
  • 2700 BCE

    First Abacus

    First Abacus
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    Uses by the blind. An adapted abacus, invented by Tim Cranmer, called a Cranmer abacus is still commonly used by individuals who are blind. A piece of soft fabric or rubber is placed behind the beads so that they do not move inadvertently. This keeps the beads in place while the users feel or manipulate them.