2.1 THE ELECTRONICS OF COMPUTERS INTEGRATED CIRCUITS The integrated circuit was invented in 1958 by Jack Kilby and Robert Noyce who came up with the idea independently and fought furiously for the rights to the invention. How big is an integrated circuit? A PCB is essentially a board that connects electronic components. Watch this silent video and see how IC, or chips, are made: From Sand to Silicon: the Making of a Chip posted by Intel copper: rame die: piastrina di materiale semiconduttore disposable: monouso to dope: drogare, trattare chimicamente fab: fabbrica to fill: riempire fingernail: unghia to mark out: delimitare pipe: tubo to peel apart: aprire, sfogliare pezzo per pezzo plant: impianto to slice: tagliare switch: interruttore, commutatore 50 The interior of a computer is made of a set of electronic circuits, called integrated circuits, built on a single small flat piece of semiconductor material, usually silicon. The integration increases speed and reduces costs if compared to the building of discrete, i.e. separate, electronic components. What is an IC? An integrated circuit (IC) or chip, is a tiny component, no bigger than a fingernail, which contains a huge amount, i.e. thousands, millions or even billions, of interconnected microelectronic devices to serve a specific function. The basic idea behind integrated circuits is to recreate a complete microscopic circuit on the surface of a piece of silicon. Electronic devices are built around a printed circuit board (PCB) which looks like an electric street map with all the electronic components, such as resistors and capacitors, in the place of buildings. Printed copper connections link them together like miniature metal streets. Although this structure is perfect for small appliances, computers require eight electronic switches to store a single byte, or character. As a consequence, the size of a computer electric plant would have been huge without the invention of the integrated circuit. THE BODY OF COMPUTERS Uses of ICs The major uses of ICs are for computer microprocessors, mobile phones, digital computer memories, and other electronic devices such as timers and sensors. How to make ICs The process of making an integrated circuit starts with a raw chemical element such as silicon, which is chemically treated, or doped, to enable it to have different electrical properties. Then, a big single crystal of silicon is shaped like a long solid pipe which is sliced into thin disks as large as a CD, called wafers. The wafers are marked out into identical square or rectangular areas, each of which will make a single silicon chip. After that, the components are created by doping different areas on the silicon surface. The die, the small block on which the circuit is fabricated, represents the IC in its smallest possible form. To make the connection of the IC possible, a package is used to encapsulate the die. The IC package turns the delicate die into the black chip we are all familiar with. Types of integrated circuits According to the way in which they are manufactured, integrated circuits can be classified as: monolithic circuits, monocrystalline, typically made of silicon; riempire hybrid circuits, which contain transistors, diodes, and other components which are difficult to manufacture with monolithic technology, and which are therefore joined to a substrate or printed circuit board.