You should always add the pull up resistor to them, it prevents accidental lock on if your grounds are floating. Gottlieb added them themselves on later games where they (still) didn't have enough driver transistors for the coils on their games.
A transistor is a semiconductor device with at least three terminals for connection to an electric circuit. In the common case, the third terminal controls the flow of current between the other two terminals. This can be used for amplification, as in the case of a radio receiver, or for rapid switching, as in the case of digital circuits. The transistor replaced the vacuum-tube triode, also called a (thermionic) valve, which was much larger in size and used significantly more power to operate.The first transistor was successfully demonstrated on December 23, 1947, at Bell Laboratories in Murray Hill, New Jersey. Bell Labs was the research arm of American Telephone and Telegraph (AT&T). The three individuals credited with the invention of the transistor were William Shockley, John Bardeen and Walter Brattain. The introduction of the transistor is often considered one of the most important inventions in history.[1][2]
The principle of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925.[4] John Bardeen, Walter Brattain and William Shockley invented the first working transistors at Bell Labs, the point-contact transistor in 1947. Shockley introduced the improved bipolar junction transistor in 1948, which entered production in the early 1950s and led to the first widespread use of transistors.
The first patent[5] for the field-effect transistor principle was filed in Canada by Austrian-Hungarian physicist Julius Edgar Lilienfeld on October 22, 1925, but Lilienfeld published no research articles about his devices, and his work was ignored by industry. In 1934 German physicist Dr. Oskar Heil patented another field-effect transistor.[6] There is no direct evidence that these devices were built, but later work in the 1990s show that one of Lilienfeld's designs worked as described and gave substantial gain. Legal papers from the Bell Labs patent show that William Shockley and a co-worker at Bell Labs, Gerald Pearson, had built operational versions from Lilienfeld's patents, yet they never referenced this work in any of their later research papers or historical articles.[7]
The Bell Lab's work on the transistor emerged from war-time efforts to produce extremely pure germanium "crystal" mixer diodes, used in radar units as a frequency mixer element in microwave radar receivers. UK researchers had produced models using a tungsten filament on a germanium disk, but these were difficult to manufacture and not particularly robust.[8] Bell's version was a single-crystal design that was both smaller and completely solid. A parallel project on germanium diodes at Purdue University succeeded in producing the good-quality germanium semiconducting crystals that were used at Bell Labs.[9] Early tube-based circuits did not switch fast enough for this role, leading the Bell team to use solid-state diodes instead.
The key to the development of the transistor was the further understanding of the process of the electron mobility in a semiconductor. It was realized that if there was some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode (discovered 1874; patented 1906), one could build an amplifier. For instance, if one placed contacts on either side of a single type of crystal, the current would not flow through it. However, if a third contact could then "inject" electrons or holes into the material, the current would flow.
Bray wrote: "That was the one aspect that we missed, but even had we understood the idea of minority carrier injection... we would have said, 'Oh, this explains our effects.' We might not necessarily have gone ahead and said, 'Let's start making transistors,' open up a factory and sell them... At that time the important device was the high back voltage rectifier".[10]
Shockley's research team initially attempted to build a field-effect transistor (FET), by trying to modulate the conductivity of a semiconductor, but was unsuccessful, mainly due to problems with the surface states, the dangling bond, and the germanium and copper compound materials. In the course of trying to understand the mysterious reasons behind their failure to build a working FET, this led them to instead inventing the bipolar point-contact and junction transistors.[11][12]
The Bell team made many attempts to build such a system with various tools, but generally failed. Setups where the contacts were close enough were invariably as fragile as the original cat's whisker detectors had been, and would work briefly, if at all. Eventually they had a practical breakthrough. A piece of gold foil was glued to the edge of a triangular plastic wedge, and then the foil was sliced with a razor at the tip of the triangle. The result was two very closely spaced contacts of gold. When the plastic was pushed down onto the surface of a crystal and voltage applied to the other side (on the base of the crystal), current started to flow from one contact to the other as the base voltage pushed the electrons away from the base towards the other side near the contacts. The point-contact transistor had been invented.
Brattain and H. R. Moore made a demonstration to several of their colleagues and managers at Bell Labs on the afternoon of 23 December 1947, often given as the birth date of the transistor. The "PNP point-contact germanium transistor" operated as a speech amplifier with a power gain of 18 in that trial. In 1956 John Bardeen, Walter Houser Brattain, and William Bradford Shockley were honored with the Nobel Prize in Physics "for their researches on semiconductors and their discovery of the transistor effect".
The way I provided the name, was to think of what the device did. And at that time, it was supposed to be the dual of the vacuum tube. The vacuum tube had transconductance, so the transistor would have 'transresistance.' And the name should fit in with the names of other devices, such as varistor and thermistor. And. . . I suggested the name 'transistor.'
Shockley was upset about the device being credited to Brattain and Bardeen, who he felt had built it "behind his back" to take the glory. Matters became worse when Bell Labs lawyers found that some of Shockley's own writings on the transistor were close enough to those of an earlier 1925 patent by Julius Edgar Lilienfeld that they thought it best that his name be left off the patent application.
Germanium was difficult to purify and had a limited operational temperature range. Scientists theorized that silicon would be easier to fabricate, but few bothered to investigate this possibility. Morris Tanenbaum et al. at Bell Laboratories[23] were the first to develop a working silicon transistor on January 26, 1954.[24] A few months later, Gordon Teal, working independently at Texas Instruments, developed a similar device. Both of these devices were made by controlling the doping of single silicon crystals while they were grown from molten silicon. A superior method was developed by Morris Tanenbaum and Calvin S. Fuller at Bell Laboratories in early 1955 by the gaseous diffusion of donor and acceptor impurities into single crystal silicon chips.[25]
Up until the late 1950s, however, germanium remained the dominant semiconductor material for transistors and other semiconductor devices. Germanium was initially considered the more effective semiconductor material, as it was able to demonstrate better performance due to higher carrier mobility.[26][27] The relative lack of performance in early silicon semiconductors was due to electrical conductivity being limited by unstable quantum surface states,[28] preventing electricity from reliably penetrating the surface to reach the semiconducting silicon layer.[29][30]
In 1955, Carl Frosch and Lincoln Derick at Bell Telephone Laboratories (BTL) accidentally discovered that silicon dioxide (SiO2) could be grown on silicon. They showed that oxide layer prevented certain dopants into the silicon wafer, while allowing for others, thus discovering the passivating effect of oxidation on the semiconductor surface.[31] In the 1950s, Mohamed Atalla, picked up Frosch's work on oxidation, investigated the surface properties of silicon semiconductors at Bell Labs, where he proposed a new method of semiconductor device fabrication, coating a silicon wafer with an insulating layer of silicon oxide so that electricity could reliably penetrate to the conducting silicon below, overcoming the surface states that prevented electricity from reaching the semiconducting layer. This is known as surface passivation, a method that became critical to the semiconductor industry as it later made possible the mass-production of silicon integrated circuits.[29] He presented his findings in 1957.[32] He studied the passivation of p-n junctions by oxide, and published his experimental results in 1957 BTL memos.[32] Atalla's surface passivation method was later the basis for two inventions in 1959: the MOS transistor by Atalla and Dawon Kahng, and the planar process by Jean Hoerni.[33]
At a 1958 Electrochemical Society meeting, Atalla presented a paper about the surface passivation of PN junctions by oxide (based on his 1957 BTL memos),[32] and demonstrated silicon dioxide's passivating effect on a silicon surface.[33] Jean Hoerni attended the same meeting, and was intrigued by Atalla's presentation. Hoerni came up with a "planar idea" one morning while thinking about Atalla's device.[32] Taking advantage of silicon dioxide's passivating effect on the silicon surface, Hoerni proposed to make transistors that were protected by a layer of silicon dioxide.[32]
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