Microprocessors

The timeline of the microprocessor is surprisingly short. In less than 70 years, we went from just having an understanding of how transistors work, to being able to cram billions of them into the size of a postage stamp. From having many circuit boards to only a small few. 

A transistor is a semiconductor used as a building block for microprocessors. They have 2 main functions, which are to act as “switches” or “amplifiers.” The first working transistor was created in 1947 by John Bardeen, Walter Brattain, and William Shockley.

A useful transistor is first implemented (single transistor) at Bell Laboratories. This electronics invention opened the way for microprocessors, and replaced the vacuum tube, which was difficult to miniaturize and wasted a lot of energy.

Microprocessors are few and expensive. They are mostly developed for very special purposes such as for the F-14 fighter jet, NASA's Interplanetary Monitoring Probe (IMP), and the Minuteman II missile guidance system.

Intel introduced the 4004, widely recognized as the first commercial microprocessor. It cost $60 USD at the time ($350 USD adjusted for inflation), and was able to execute 50,000 instructions a second (2,300 transistors).

Intel’s 8086, a 16 bit microprocessor with 29,000 transistors, was released. This chip’s instruction set is still at the center of most computers built today and transformed Intel into the world’s largest chip company.

IBM’s Deep Blue computer beat Chess Master Garry Kasparov for the first time. The Deep Blue program was capable of analyzing 200 million positions per second and served as yet another example of how powerful microprocessors were becoming.

Advanced Micro Devices (AMD), Intel’s primary rival in designing and building microprocessors, released the Athlon 64, a 64-bit chip with 65 million transistors. It was AMD’s first 64-bit processor created for average consumers.

Today’s cell phone has as much computing power as a supercomputer from 2 decades ago. There are even microprocessors that we can wear on our wrists.

With its very first iPhone release, which was recognized as Invention of the Year by Time magazine, Apple was pretty much able to store a computer on a phone. This was possible by using mobile–specific chips. 

A transistor is the smallest functioning unit in a processor. Being the basic building block of a microprocessor, it performs a very simple logic operation when a voltage is applied. When billions of these transistors work in sync, they can do amazing things.

Diodes direct the flow of electricity. Electric current can only travel one way in a diode due to its polarized ends. On one end, the anode, is positive; on the other, the cathode is negative. Current can only flow from the anode to the cathode, never in reverse. 

BJT transistors are comprised of 3 basic sections, the “Collector,” the “Base,” and the “Emitter.” The base controls the current flow. The emitter either releases electrons or emits “holes” which are gaps where there are no electrons. 

The collector receives the electrons released by the emitter or fills the holes left by the absence of electrons. 

Transistors have 4 ways in which the current can flow. In ”Saturation”: the current runs freely from emitter to collector.  In “Cut-off”: the current flow is stopped completely. In “Active”: the current is only partially flowing based on the current flowing through the base. 

In “Reverse-active”: The same as Active, just the current is flowing in reverse.