Transistor Evolution and Processor Revolution
The microprocessor manufacturing process is inextricably linked with the evolution and continuous improvement of the transistor. The transistor, invented in 1948 in the laboratories of Bell Corporation, made it possible to create a computer from small-sized electronic circuits created on printed circuit boards. The revolutionary role of the transistor is in its small size. The combination of a large number of such transistors on a PCB made it possible to create separate nodes and even entire devices. The use of transistors made it possible to reduce the size of computers and increase their computing power. However, the dimensions of the computer on transistors still remained very large for their widespread use. But from the point of view of the technological process there is no particular difference whether to make one transistor on a substrate or a lot at once. Having produced a sufficient number of transistors on one substrate, one step remains before turning several transistors into an integrated circuit – to connect the obtained transistors in a certain way. And such a revolutionary step was taken exactly 10 years after the invention of the transistor. The first true integrated circuit was released in 1958 by Texas Instruments.
With the naked eye, differences are visible. In the left photo, neither the technical process nor the design of the product were thought about.
Integrated circuits have gradually become an integral part of almost any electronic device, including computers. Computers began to be used not only for scientific calculations, but also in business. But these were still very bulky and expensive devices.
11 years after the release of the first integrated circuit, another revolution occurred: a microprocessor appeared. In 1969, Intel had just received an order from Busicom, a Japanese company, to develop 12 specialized chips for an accounting calculator. Instead of these chips, Intel engineers, led by Gordon Moore and Robert Noyce, developed a general-purpose microprocessor designed for use in calculators. It was a single-chip microprocessor called 4004 (4-bit data bus and 16-pin package).
With the advent of microprocessors, the evolution of transistors, of which, in fact, any microcircuit consists, did not stop. The struggle for the purity of the initial silicon wafers continues. The process of introducing alloying impurities becomes more accurately dosed. This allows you to constantly improve the frequency properties of transistors. But the real battle unfolded on the front of improving the resolution of the photolithography process, which underlies the production of microcircuits. This is the so-called “technological norm” of the technological process. It determines the minimum size of the elements that can be formed on the plate. When they say, for example, about 0.18 μm technology, it means the value of the norm of the technological process is 0.18 μm.
The i8088 processor, the ancestor of most processors for personal computers, consisted of 29 thousand transistors, was manufactured using 3-micron technology and had a total substrate area of 33 mm2. For comparison, the modern Pentium 4 processor consists of 42 million transistors, is produced by the 0.18-micron process technology and has an area of 217 mm2. The matrix of the P4 processor has 1400 times more transistors than the processor of the 8088, but the surface area of its core is only 7 times the size of the 8088 core!
Improving the technology for the production of microprocessors has significantly increased their clock frequency. Each new generation of processors has a lower supply voltage and lower currents, which helps to reduce the heat generated by them. But the most important achievement is that when the rate of the process is reduced, the number of transistors per crystal can be significantly increased. A larger number of transistors included in the processor allows you to improve the processor architecture in order to achieve even greater performance. Even the processor capacity increased very quickly from 4 in the first processor to 32 in the i386 processor.
A significant milestone in the history of the architecture of personal computer processors (the next revolution) was the emergence of the i486 processor. By that time, the manufacturing process had reached 1 micron, which made it possible to position 1.5 million transistors in the processor core, which was almost 6 times more than the CPU of the previous 386th generation. This allowed the introduction of truly revolutionary changes in the processor architecture:
In the architecture of the processor of a personal computer, a pipeline for five stages first appeared. Pipeline computing was, of course, known long before the advent of personal computers, but the high degree of integration now enabled the use of this efficient method of computing in a personal computer.