There is a cross rod to divide beads into two parts, above the rod each bead represents quantities of five, while under the rod each bead represents quantities of one. It has a rectanglular wooden frame with beads in columns (nowadays you also can find abacus made with plastic or other materials rather than wood). The abacus is similar to the modern calculator. The abacus is a tool for calculating numbers, and was widely used in ancient times up to the invention of the modern mechanical and electronic calculators. ![]() The abacus was first mentioned (possibly improved upon, but not invented) by the mathematician Xu Yueh (徐岳) at the end of Eastern Han Dynasty (25-220 A.D). Smart phones can now do the following: handle phone calls, take pictures, run apps, do calculations, browse the internet, etc.The Chinese Abacus.Examples are GPS units, tablets, smart phones.In early 2000’s there was an explosion of handheld computers.We can now to go to our favorite websites, to order products, to communicate via email or facebook, etc.The World Wide Web allowed us to connect to servers across the world.In 1981, the IBM PC was created and shortly after Microsoft was formed and the MS-DOS operating system was created.At this time Visicalc (spreadsheet program) was created for the Apple.Meanwhile Steve Wozniak and Steve Jobs were busy creating the Apple II in 1977.Also in 1975, Bill Gates, Paul Allen, and Monte Davidoff wrote BASIC programming language.Altair 8800 created in 1975 as a mail-order kit.All chips needed for the CPU were put together on one chip.In the 1971, engineers from Intel Corporation designed the first microprocessor.Advanced the integrated circuit even further.Instead of soldering components after the are made, they were manufactured all together on a chip of silicon.In the late 1950s, engineers from Texas Instruments created integrated circuit.Relied on other electronic components to form circuits Portable transistor radio.Much smaller, faster and more reliable.In 1947, engineers from Bell Laboratories invented the transistor.Hopper “debugged” the computer byremoving the moth. The original “bug” was a moth that was lodged in the circuitry and created a hardware problem in a Mark I computer. Where did the term "bug" come from? Grace Hopper coined the term “bug” when there was a computer malfunction. ![]() Used vacuum tubes (slow/hot, similar to light bulbs).VERY expensive and HUGE – required large rooms and a lot of A/C.It was the first general purpose computer. In 1951, the UNIVAC was first mass-produced. ![]() They were VERY expensive and used enough electricity to light up a small town.The early computers used punched cards. ![]() They were used to calculate weapon trajectories and help build atomic bombs.
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