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In a brief period of our history occurred the remarkable development and growth of the computer technology we take for granted today
THE PRACTICALITY OF THE SILICON INTEgrated circuit pretty well began with early TTL, or T2L, as it is universally called. The difficulty was that of making the devices small enough so that many of them could be squeezed onto a small piece of a silicon wafer.
The entire IC technology developed at an amazingly rapid pace, once the first ICs were created. Before the IC, the silicon transistor required that the business of growing a single silicon crystal be solved. This crystal had to be extremely pure, and all atoms had to form a single lattice in order for the transistor to work.
The first crystals were only about an inch in diameter and were then sliced into thin wafers. The surface of the wafer became the place where selective doping of N and P type atoms were introduced to form the parts of the transistors. Then the concept of interconnecting devices to make an IC became the big challenge. Layers of metalization and silicon dioxide insulation had to be placed on the top of the devices and selectively etched away to leave the desired conductor pattern.
Everything was and is microscopic in nature, and grows smaller year by year as the technology improves. Something like the microprocessor chip in the modern computer contains hundres of thousands of tiny devices. The original T2L devices were called SSI, meaning small-scale integration. Then came MSI, medium-scale integration, followed by LSI, large-scale integration. VLSI for very large-scale integration came next, and each of these steps permitted more devices on the same piece of silicon "real estate."
When the MOSFET came along, a real breakthrough occurred. The amount of silicon surface needed to create a MOSFET is only a fraction of that needed for a bipolar transistor. Approximately ten MOSFETs can be placed in the space needed for one bipolar transistor. One of the early problems encountered when designing with T2L (TTL) was its demand for current. The original T2L series' thirst for current made the power supply pretty beefy. These chips are the ones in the 54/74 series, and they dissipate about 10 milliwatts...