This week's lessons on computer hardware development can be difficult to grasp without looking at some of this material with your eyeballs.
Intel has a free museum at their headquarters in Santa Clara, California. It's just a half hour from my office, so my son and I rode our bikes there for a field trip during our lessons on early computer technology and semiconductors.
At the Intel Museum, you can see Intel's semiconductor memory chips next to some core memory (an early type of computer memory that used wire windings around tiny iron donuts to store information). You can touch a big blob of purified silicon crystal and silicon wafers from which modern semiconductor integrated circuits are manufactured. Interactive exhibits describe the process of designing and manufacturing computer chips in details.
If you live in or near Silicon Valley, it's worth the trip. Parking is free -- just follow the signs for visitor / museum parking. Intel is served by VTA 60 (the bus that runs between the Winchester Transit Center in Campbell to Great America) and the free Mission Shuttle from Lawrence Caltrain. Intel HQ is also a very easy ride from the San Tomas Aquino bike trail, with bike racks available left of the museum entrance and on the ground level of the employee parking garage.
The guided tours are geared for grade school level children, so teens should do the self guided tour. Give yourselves about an hour. I had my son write a trip report. He's a visual learner, so the biggest benefit for him was seeing this old and new technology first hand.
Intel also has a nice resource covering much of this material in their online Journey Inside computer education curriculum. Use this to supplement your student's computer education with lessons computer history, the parts of a computer, circuits and switches, semiconductors, digital information, microprocessors, the Internet, and technology's impact on society.
In addition to Intel's museum in Santa Clara, we have a Computer History Museum and the Tech Museum of Innovation in Silicon Valley.
Finally, for those outside of Silicon Valley, see if there's a technology museum near you.
Showing posts with label computer history. Show all posts
Showing posts with label computer history. Show all posts
Monday, August 29, 2011
Lesson 2: Tubes and Transistors
A way to switch circuits on and off is necessary to create electronic digital computers. Some of the earliest electronic computers used mechanical relays controlled by paper tape with holes punched into it to add, substract, multiply, divide and calculate logarithmic and trigonometric functions.
Relays were replaced with vacuum tubes early on, then transistors. Small personal computers became possible with the invention of the integrated circuit, which can place many many transistors onto a single, small chip of silicon.
We will discuss how electronic switching is used in computing later, but first we'll cover the basics of the hardware technology that makes electronic binary logic possible.
Vacuum tubes are simple, electronic devices through which electrons -- and, hence, electricty -- flows through a vacuum. The most basic tube consists of a cathode and an anode inside of the vacuum tube.
Heating the cathode energizes the electrons in the metal filament there. The electrons leave the cathode and jump into the surrounding space. As negatively charged electrons leave, they are attracted to the positively charged anode.
(Diagram from Vacuum Tube Basics, where you can learn more about vacuum tube operation.)
It's possible to control the flow of electricity by adding a grid between the cathode and anode. When a negative charge is applied to this grid, electrons from the cathode are repelled and cannot travel to the anode and, so, no electrical current can flow across the tube. This control grid acts as an electronic on-off switch. This on-off switching function is a necessary component for digital computers.
The next step of electronics development involved materials called semiconductors. At the most basic level, semiconductors are materials with an electrical conductivity somewhere between conductors (such as metal wires) and insulators (such as rubber or glass). What makes semiconductors useful for electronics is the ability to control the electronic properties and conductivity through "doping," which is adding small amounts of other elements to the semiconductor.
Early crystal radio receivers used a Cat's whisker detector. These detectors used a thin wire touching a semiconductor crystal to pick up radio signals. These early semiconductors were unreliable, however, and were soon superseded with vacuum tube technology.
A Bell Labs researcher studying radar technology at the outbreak of World War II accidentally invented the first semiconductor diode in 1939 when he purified semiconductor crystals used for Cat's Whiskers. After nearly another decade of concerted effort, the first semiconductor transistor was demonstrated at Bell Labs in 1947.
Later research showed the transistor could be used like a switch like a vacuum tube. Transistors are much smaller than vacuum tubes, use significantly less power, are more reliable, and (eventually) less expensive to manufacture. It didn't take long for hobbyists and computer engineers to figure out they could create smaller computers with transistors instead of vacuum tubes.
Vacuum tubes use tremendous amounts of energy to keep the cathodes hot, and they were fragile, with thin filaments prone to burning out. Semiconductor materials enable much more reliable electronic devices that use much less power.
Transistors are used with other types of discrete electronic components such as resistors, capacitors, and diodes and connected with wiring and printed circuit board circuit traces to create electronic devices such as radios, calculators and computers. When you see the green (usually, but they can be brown, red, or yellow) circuit board with big gobs of solder inside of an an electronic house thermostat or a toy R/C car, most of the electronic parts stickup up from one side of that board are discrete components.
The next big step in electronics miniaturization was the development of the integrated circuit, which we'll cover in the next lesson.
Relays were replaced with vacuum tubes early on, then transistors. Small personal computers became possible with the invention of the integrated circuit, which can place many many transistors onto a single, small chip of silicon.
We will discuss how electronic switching is used in computing later, but first we'll cover the basics of the hardware technology that makes electronic binary logic possible.
Vacuum Tubes
Vacuum tubes are simple, electronic devices through which electrons -- and, hence, electricty -- flows through a vacuum. The most basic tube consists of a cathode and an anode inside of the vacuum tube.
Heating the cathode energizes the electrons in the metal filament there. The electrons leave the cathode and jump into the surrounding space. As negatively charged electrons leave, they are attracted to the positively charged anode.
(Diagram from Vacuum Tube Basics, where you can learn more about vacuum tube operation.)
It's possible to control the flow of electricity by adding a grid between the cathode and anode. When a negative charge is applied to this grid, electrons from the cathode are repelled and cannot travel to the anode and, so, no electrical current can flow across the tube. This control grid acts as an electronic on-off switch. This on-off switching function is a necessary component for digital computers.
Semconductors
The next step of electronics development involved materials called semiconductors. At the most basic level, semiconductors are materials with an electrical conductivity somewhere between conductors (such as metal wires) and insulators (such as rubber or glass). What makes semiconductors useful for electronics is the ability to control the electronic properties and conductivity through "doping," which is adding small amounts of other elements to the semiconductor.
Early crystal radio receivers used a Cat's whisker detector. These detectors used a thin wire touching a semiconductor crystal to pick up radio signals. These early semiconductors were unreliable, however, and were soon superseded with vacuum tube technology.
A Bell Labs researcher studying radar technology at the outbreak of World War II accidentally invented the first semiconductor diode in 1939 when he purified semiconductor crystals used for Cat's Whiskers. After nearly another decade of concerted effort, the first semiconductor transistor was demonstrated at Bell Labs in 1947.
Transistors
Later research showed the transistor could be used like a switch like a vacuum tube. Transistors are much smaller than vacuum tubes, use significantly less power, are more reliable, and (eventually) less expensive to manufacture. It didn't take long for hobbyists and computer engineers to figure out they could create smaller computers with transistors instead of vacuum tubes.
Vacuum tubes use tremendous amounts of energy to keep the cathodes hot, and they were fragile, with thin filaments prone to burning out. Semiconductor materials enable much more reliable electronic devices that use much less power.
Transistors are used with other types of discrete electronic components such as resistors, capacitors, and diodes and connected with wiring and printed circuit board circuit traces to create electronic devices such as radios, calculators and computers. When you see the green (usually, but they can be brown, red, or yellow) circuit board with big gobs of solder inside of an an electronic house thermostat or a toy R/C car, most of the electronic parts stickup up from one side of that board are discrete components.
The next big step in electronics miniaturization was the development of the integrated circuit, which we'll cover in the next lesson.
Sunday, August 28, 2011
Lesson 1: Student Assignment
Some of the below questions are review of Lesson 1: "Early Computer History." Some will require further research to answer.
1. What did Joseph-Marie Jacquard invent?
2. Describe Charles Babbage's Analytical Machine?
3. Why is Ada Lovelace important? What computer language was named in her honor?
4. What is Herman Hollerith famous for?
5. List the characteristics of a Turing Machine.
6. How is the Harvard Architecture different from a von Neumann Architecture?
7. In George Stibitz's Model K computer, what does the "K" stand for?
8. A machine called "ABC" was developed at the University of Iowa. What does ABC stand for?
9. What does ENIAC stand for?
10. Who popularized the word "bug" in the context of computer programs? What kind of bug was noted in her journal?
1. What did Joseph-Marie Jacquard invent?
2. Describe Charles Babbage's Analytical Machine?
3. Why is Ada Lovelace important? What computer language was named in her honor?
4. What is Herman Hollerith famous for?
5. List the characteristics of a Turing Machine.
6. How is the Harvard Architecture different from a von Neumann Architecture?
7. In George Stibitz's Model K computer, what does the "K" stand for?
8. A machine called "ABC" was developed at the University of Iowa. What does ABC stand for?
9. What does ENIAC stand for?
10. Who popularized the word "bug" in the context of computer programs? What kind of bug was noted in her journal?
Lesson 1: Early Computer History
Here's a quick overview of computer history. I taught this lesson in a single one hour session, but you can explore further in the links and probably expand this into an entire semester if you wanted.
1801 Joseph-Marie Jacquard exhibits his Jackquard Loom, which uses punched cards to control a sequence of operations to make different fabric patterns. Jacquard is credited as the inventor of the first programmable machine. His loom is not a computer, but this loom is an important predecessor in the development of programmable computers.
1837 Charles Babbage describes his proposal for a programmable Analytical Engine, which can be programmed with punch cards to solve mathematical equations. Mathematician Ada Lovelance worked with Babbage and is credited as the first computer programmer. In 1979, the computer language Ada was named in her honor. Babbage was never able to build a working Analytical Engine.
1890 Herman Hollerith develops tabulating machines that uses punch cards to complete the U.S. census in record time. Hollerith founds the "Tabulating Machine Company" which, after various mergers, eventually becomes IBM.
1936 British mathemetician Alan Turing describes the Turing Machine, an important step in the development of computer science theory. The Turing Machine is used to help computer scientists model processing behavior and algorithms.
1937 Bell Labs researcher George Stibitz creates a calculator he calls the "Model K" which used Boolean logic mechanical relays. (We'll cover Boolean logic later)
1939 University of Iowa researchers pioneer important computing concepts with the Atanasoff Berry Computer, including binary arithmetic and electronic switching.
1940s Computer hardware development explodes due to World War 2. Norden bomb sight and artillery fire control are some examples of mechanical computers used in warfare. The British built 10 Colossus computer -- large, building sized electronic digital computers -- to break German codes. They used thousands of vacuum tubes to perform calculations, and data was input using paper tape with holes punched into them, which controlled the movement of metal wheels with pins on them.
1943 ENIAC -- the first general purpose electronic computer.
1945 Mathemetician John von Neumann describes the von Neumann architecture. This describes your basic stored program computer with an arithmetic unit, control unit, a common memory to store data and programming, input and output, and external storage. Instructions and data are fetched via a common bus (or data transfer circuit). von Neumann's store program architecture was an advancement over earlier program controlled computers, which were programmed by hard wiring the instructions as part of the computer architecture.
1950s - first commercial computers developed.
1801 Joseph-Marie Jacquard exhibits his Jackquard Loom, which uses punched cards to control a sequence of operations to make different fabric patterns. Jacquard is credited as the inventor of the first programmable machine. His loom is not a computer, but this loom is an important predecessor in the development of programmable computers.
1837 Charles Babbage describes his proposal for a programmable Analytical Engine, which can be programmed with punch cards to solve mathematical equations. Mathematician Ada Lovelance worked with Babbage and is credited as the first computer programmer. In 1979, the computer language Ada was named in her honor. Babbage was never able to build a working Analytical Engine.
1890 Herman Hollerith develops tabulating machines that uses punch cards to complete the U.S. census in record time. Hollerith founds the "Tabulating Machine Company" which, after various mergers, eventually becomes IBM.
1936 British mathemetician Alan Turing describes the Turing Machine, an important step in the development of computer science theory. The Turing Machine is used to help computer scientists model processing behavior and algorithms.
1937 Bell Labs researcher George Stibitz creates a calculator he calls the "Model K" which used Boolean logic mechanical relays. (We'll cover Boolean logic later)
1939 University of Iowa researchers pioneer important computing concepts with the Atanasoff Berry Computer, including binary arithmetic and electronic switching.
1940s Computer hardware development explodes due to World War 2. Norden bomb sight and artillery fire control are some examples of mechanical computers used in warfare. The British built 10 Colossus computer -- large, building sized electronic digital computers -- to break German codes. They used thousands of vacuum tubes to perform calculations, and data was input using paper tape with holes punched into them, which controlled the movement of metal wheels with pins on them.
1943 ENIAC -- the first general purpose electronic computer.
1945 Mathemetician John von Neumann describes the von Neumann architecture. This describes your basic stored program computer with an arithmetic unit, control unit, a common memory to store data and programming, input and output, and external storage. Instructions and data are fetched via a common bus (or data transfer circuit). von Neumann's store program architecture was an advancement over earlier program controlled computers, which were programmed by hard wiring the instructions as part of the computer architecture.
1950s - first commercial computers developed.
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