Another experience was that I took a welding shop class because I wanted to learned to be a better arc welder at my college. But, at the time then in 1975 I often still wore bell bottom jeans with frayed cuffs as was still the style that many wore then. But, I didn't consider the fact that frayed bell bottoms and arc welder sparks don't mix in any useful way. So, because I rode my dualsport Honda 250 XL to college that day I had my knee high cowboy boots to protect my legs when I rode off road or if I crashed so I wouldn't pin my leg or foot and have it ground off by the road by the motorcycle. So, because I had knee high cowboy boots as well as frayed Levi Jeans that were bell bottoms on the sparks from the arc welder set my cuff on one pant leg on fire. So, as I welded I thought my boots felt kind of hot on the right side. When I finally looked down I was on fire so I stopped welding and put the fire out. It was sort of embarrassing to ride home with a 6 inch or larger circle of charred Bells on my right pant leg but at least I didn't get burned anywhere just my right pant leg.
It's really amazing to me all the really crazy things that can happen in your life. Also, I realized I shouldn't carry a BIC butane Lighter in my right front pants pocket either then because one spark could make my right thigh blow up with the butane. So, that day I stopped carrying a Bic lighter in my pants as long as I was in my welding class at college.
Welding was the only class I took of this kind in college mostly I as studying then psychology, philosophy and anthropology during this segment of my life. MY previous experience with college I had majored in Business Data Processing and worked on punch card equipment and IBM 1620 and IBM 360 Mainframe computers and had worked in the computer field as a programmer and as a computer operator. However, I sort of burned out doing that as there was no random access memory then and I found I couldn't really do what I really wanted to with computers until computer chips were invented in the 1970s. And even then Apple Computers didn't really get going until:
The company was founded on April 1, 1976, and incorporated as Apple Computer, Inc. on January 3, 1977.[6] end quote from wikipedia under the heading apple computer.
Here is part of the history of computer chips from Wikipedia:
SSI, MSI and LSI
The first integrated circuits contained only a few transistors. Called "small-scale integration" (SSI), digital circuits containing transistors numbering in the tens provided a few logic gates for example, while early linear ICs such as the Plessey SL201 or the Philips TAA320 had as few as two transistors. The term Large Scale Integration was first used by IBM scientist Rolf Landauer when describing the theoretical concept[citation needed], from there came the terms for SSI, MSI, VLSI, and ULSI.SSI circuits were crucial to early aerospace projects, and aerospace projects helped inspire development of the technology. Both the Minuteman missile and Apollo program needed lightweight digital computers for their inertial guidance systems; the Apollo guidance computer led and motivated the integrated-circuit technology,[16] while the Minuteman missile forced it into mass-production. The Minuteman missile program and various other Navy programs accounted for the total $4 million integrated circuit market in 1962, and by 1968, U.S. Government space and defense spending still accounted for 37% of the $312 million total production. The demand by the U.S. Government supported the nascent integrated circuit market until costs fell enough to allow firms to penetrate the industrial and eventually the consumer markets. The average price per integrated circuit dropped from $50.00 in 1962 to $2.33 in 1968.[17] Integrated circuits began to appear in consumer products by the turn of the decade, a typical application being FM inter-carrier sound processing in television receivers.
The next step in the development of integrated circuits, taken in the late 1960s, introduced devices which contained hundreds of transistors on each chip, called "medium-scale integration" (MSI).
They were attractive economically because while they cost little more to produce than SSI devices, they allowed more complex systems to be produced using smaller circuit boards, less assembly work (because of fewer separate components), and a number of other advantages.
Further development, driven by the same economic factors, led to "large-scale integration" (LSI) in the mid-1970s, with tens of thousands of transistors per chip.
Integrated circuits such as 1K-bit RAMs, calculator chips, and the first microprocessors, that began to be manufactured in moderate quantities in the early 1970s, had under 4000 transistors. True LSI circuits, approaching 10,000 transistors, began to be produced around 1974, for computer main memories and second-generation microprocessors.
VLSI
Main article: Very-large-scale integration
Multiple developments were required to achieve this increased density. Manufacturers moved to smaller design rules and cleaner fabrication facilities, so that they could make chips with more transistors and maintain adequate yield. The path of process improvements was summarized by the International Technology Roadmap for Semiconductors (ITRS). Design tools improved enough to make it practical to finish these designs in a reasonable time. The more energy efficient CMOS replaced NMOS and PMOS, avoiding a prohibitive increase in power consumption.
In 1986 the first one megabit RAM chips were introduced, which contained more than one million transistors. Microprocessor chips passed the million transistor mark in 1989 and the billion transistor mark in 2005.[18] The trend continues largely unabated, with chips introduced in 2007 containing tens of billions of memory transistors.[19]
ULSI, WSI, SOC and 3D-IC
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Wafer-scale integration (WSI) is a system of building very-large integrated circuits that uses an entire silicon wafer to produce a single "super-chip". Through a combination of large size and reduced packaging, WSI could lead to dramatically reduced costs for some systems, notably massively parallel supercomputers. The name is taken from the term Very-Large-Scale Integration, the current state of the art when WSI was being developed.
A system-on-a-chip (SoC or SOC) is an integrated circuit in which all the components needed for a computer or other system are included on a single chip. The design of such a device can be complex and costly, and building disparate components on a single piece of silicon may compromise the efficiency of some elements. However, these drawbacks are offset by lower manufacturing and assembly costs and by a greatly reduced power budget: because signals among the components are kept on-die, much less power is required (see Packaging).
A three-dimensional integrated circuit (3D-IC) has two or more layers of active electronic components that are integrated both vertically and horizontally into a single circuit. Communication between layers uses on-die signaling, so power consumption is much lower than in equivalent separate circuits. Judicious use of short vertical wires can substantially reduce overall wire length for faster operation.
Advances in integrated circuits
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ICs have consistently migrated to smaller feature sizes over the years, allowing more circuitry to be packed on each chip. This increased capacity per unit area can be used to decrease cost and/or increase functionality—see Moore's law which, in its modern interpretation, states that the number of transistors in an integrated circuit doubles every two years. In general, as the feature size shrinks, almost everything improves—the cost per unit and the switching power consumption go down, and the speed goes up. However, ICs with nanometer-scale devices are not without their problems, principal among which is leakage current (see subthreshold leakage for a discussion of this), although these problems are not insurmountable and will likely be solved or at least ameliorated by the introduction of high-k dielectrics. Since these speed and power consumption gains are apparent to the end user, there is fierce competition among the manufacturers to use finer geometries. This process, and the expected progress over the next few years, is well described by the International Technology Roadmap for Semiconductors (ITRS).
In current research projects, integrated circuits are also developed for sensoric applications in medical implants or other bioelectronic devices. Particular sealing strategies have to be taken in such biogenic environments to avoid corrosion or biodegradation of the exposed semiconductor materials.[20] As one of the few materials well established in CMOS technology, titanium nitride (TiN) turned out as exceptionally stable and well suited for electrode applications in medical implants.[21][22]
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