Museum Report 2017-11-26 November 26, 2017
Lots of visitors today about 2 dozen. I show the kids a Macintosh and tell them to run Paint. They try to touch the screen. They think it is a touch screen. Then I show them the mouse. They single click. The don't know double click that well. I have to explain to them how slow computers were and they have to wait. I show the kids BASIC, then Impossible Mission on the C64. They love it. I show them Windows 3.1 and they love Minesweeper and Solitaire. They all loved it and stayed for an hour as I showed them the different microcomputers. I actually did a lot of tours instead of the usual quick run through. Lots of interest and they learned a lot about the history of computers that they didn't know. The parents love the explanation of the progression of technology. I need to learn more about how vacuum tube computers work to give them a comparison. Spent the rest of the time inventorying supplies we have for Festivus that we have already.
On 11/26/2017 04:54 PM, Jeffrey Brace via vcf-midatlantic wrote:
The parents love the explanation of the progression of technology. I need to learn more about how vacuum tube computers work to give them a comparison.
It's important to realize that there's really no difference. Vacuum tubes are analogous to FETs (field-effect transistors) and are simply the active switching element of tube-based digital computers, where transistors are the active switching element of solid-state computers. The logic...the instruction set, buses, etc...can be identical. The only real reason they're not is because computer architecture has grown up alongside, but largely independent of, electronics technology. Now if you're talking about tube-based analog computers, that's a different animal...and the same point applies there. Analog computers are (mostly) composed of op-amps, and those op-amps can be built with tubes or transistors. (with or without multiple transistors being "integrated" into one "circuit", i.e. using integrated circuits) Again, the architecture is (or at least can be) the same. The takeaway here is the importance of understanding the difference between architectures and implementations. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
How would you explain the George Philbrick machine to an 8 year old? How do you explain what a vacuum tube actually does to an 8 year old? On Sun, Nov 26, 2017 at 8:50 PM, Dave McGuire via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On 11/26/2017 04:54 PM, Jeffrey Brace via vcf-midatlantic wrote:
The parents love the explanation of the progression of technology. I need to learn more about how vacuum tube computers work to give them a comparison.
It's important to realize that there's really no difference. Vacuum tubes are analogous to FETs (field-effect transistors) and are simply the active switching element of tube-based digital computers, where transistors are the active switching element of solid-state computers. The logic...the instruction set, buses, etc...can be identical. The only real reason they're not is because computer architecture has grown up alongside, but largely independent of, electronics technology.
Now if you're talking about tube-based analog computers, that's a different animal...and the same point applies there. Analog computers are (mostly) composed of op-amps, and those op-amps can be built with tubes or transistors. (with or without multiple transistors being "integrated" into one "circuit", i.e. using integrated circuits) Again, the architecture is (or at least can be) the same.
The takeaway here is the importance of understanding the difference between architectures and implementations.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
8 yrs is probably too young for us to explain any such details. With a child that young, I just tell them computers used to be this large when their grandparents or greatgrandparents were their age, and leave it at that. For teens or precocious adolescents (or clueless adults!), I explain that a vacuum tube is simply a predessor to transistors but that it does the same basic thing: it gets electrified to represent a digital 1 or turned off for a digital 0. If they want to know how a tube or transistor * actually works * then I suggest they visit the radio museum. :) On Nov 26, 2017 9:13 PM, "Jeffrey Brace via vcf-midatlantic" < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
How would you explain the George Philbrick machine to an 8 year old? How do you explain what a vacuum tube actually does to an 8 year old?
On Sun, Nov 26, 2017 at 8:50 PM, Dave McGuire via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On 11/26/2017 04:54 PM, Jeffrey Brace via vcf-midatlantic wrote:
The parents love the explanation of the progression of technology. I need to learn more about how vacuum tube computers work to give them a comparison.
It's important to realize that there's really no difference. Vacuum tubes are analogous to FETs (field-effect transistors) and are simply the active switching element of tube-based digital computers, where transistors are the active switching element of solid-state computers. The logic...the instruction set, buses, etc...can be identical. The only real reason they're not is because computer architecture has grown up alongside, but largely independent of, electronics technology.
Now if you're talking about tube-based analog computers, that's a different animal...and the same point applies there. Analog computers are (mostly) composed of op-amps, and those op-amps can be built with tubes or transistors. (with or without multiple transistors being "integrated" into one "circuit", i.e. using integrated circuits) Again, the architecture is (or at least can be) the same.
The takeaway here is the importance of understanding the difference between architectures and implementations.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
Jeff Get an old smart phone and open it up to expose the circuit board, show to the visitor and ask the person to note how small the individual components are, like a little city. Many differnt types of components Then, say before computer board components got small enough to make things like smart phones possible they used tubes and other larger components to do the same sort of things. Tubes used a lot more power and generated a lot more heat than today's equivalents. If a smart phone was full of tubes and associated 50's era components instead of today's smaller components the phone would have to be the size of Camp Evans. The MIT machine we have in the museum display is not anything like a cell phone however it's an analog computer sort of. Its more actually a bunch of Philco analog rack units that would have been part of a larger system plus a plotter and instruments generating "input". I have materials at my house that explain some of the rack components I promise next time I come up I'll try to put something together to explain what the MIT computer likely would have done. Also, as they are now the rack components are in a disorganized impractical configuration. We need to put them together into a more likely configuration asap. That would be a good thing to do next workshop. The process of researching the components will help expose it's function and help docents explain it. As Dave said, an analog computer used tubes for different reasons than a digital computer with logic tubes. There were many different kinds of tubes then, as today there are different kinds of transistors. Bill Degnan twitter: billdeg vintagecomputer.net On Nov 26, 2017 9:22 PM, "Evan Koblentz via vcf-midatlantic" < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
8 yrs is probably too young for us to explain any such details. With a child that young, I just tell them computers used to be this large when their grandparents or greatgrandparents were their age, and leave it at that. For teens or precocious adolescents (or clueless adults!), I explain that a vacuum tube is simply a predessor to transistors but that it does the same basic thing: it gets electrified to represent a digital 1 or turned off for a digital 0. If they want to know how a tube or transistor * actually works * then I suggest they visit the radio museum. :)
On Nov 26, 2017 9:13 PM, "Jeffrey Brace via vcf-midatlantic" < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
How would you explain the George Philbrick machine to an 8 year old? How do you explain what a vacuum tube actually does to an 8 year old?
On Sun, Nov 26, 2017 at 8:50 PM, Dave McGuire via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On 11/26/2017 04:54 PM, Jeffrey Brace via vcf-midatlantic wrote:
The parents love the explanation of the progression of technology. I need to learn more about how vacuum tube computers work to give them a comparison.
It's important to realize that there's really no difference. Vacuum tubes are analogous to FETs (field-effect transistors) and are simply the active switching element of tube-based digital computers, where transistors are the active switching element of solid-state computers. The logic...the instruction set, buses, etc...can be identical. The only real reason they're not is because computer architecture has grown up alongside, but largely independent of, electronics technology.
Now if you're talking about tube-based analog computers, that's a different animal...and the same point applies there. Analog computers are (mostly) composed of op-amps, and those op-amps can be built with tubes or transistors. (with or without multiple transistors being "integrated" into one "circuit", i.e. using integrated circuits) Again, the architecture is (or at least can be) the same.
The takeaway here is the importance of understanding the difference between architectures and implementations.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
Oops I did not mean "Philco" Bill Degnan twitter: billdeg vintagecomputer.net On Nov 26, 2017 10:57 PM, "william degnan" <billdegnan@gmail.com> wrote:
Jeff
Get an old smart phone and open it up to expose the circuit board, show to the visitor and ask the person to note how small the individual components are, like a little city. Many differnt types of components Then, say before computer board components got small enough to make things like smart phones possible they used tubes and other larger components to do the same sort of things. Tubes used a lot more power and generated a lot more heat than today's equivalents.
If a smart phone was full of tubes and associated 50's era components instead of today's smaller components the phone would have to be the size of Camp Evans.
The MIT machine we have in the museum display is not anything like a cell phone however it's an analog computer sort of. Its more actually a bunch of Philco analog rack units that would have been part of a larger system plus a plotter and instruments generating "input". I have materials at my house that explain some of the rack components I promise next time I come up I'll try to put something together to explain what the MIT computer likely would have done. Also, as they are now the rack components are in a disorganized impractical configuration. We need to put them together into a more likely configuration asap. That would be a good thing to do next workshop. The process of researching the components will help expose it's function and help docents explain it.
As Dave said, an analog computer used tubes for different reasons than a digital computer with logic tubes. There were many different kinds of tubes then, as today there are different kinds of transistors.
Bill Degnan twitter: billdeg vintagecomputer.net On Nov 26, 2017 9:22 PM, "Evan Koblentz via vcf-midatlantic" < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
8 yrs is probably too young for us to explain any such details. With a child that young, I just tell them computers used to be this large when their grandparents or greatgrandparents were their age, and leave it at that. For teens or precocious adolescents (or clueless adults!), I explain that a vacuum tube is simply a predessor to transistors but that it does the same basic thing: it gets electrified to represent a digital 1 or turned off for a digital 0. If they want to know how a tube or transistor * actually works * then I suggest they visit the radio museum. :)
On Nov 26, 2017 9:13 PM, "Jeffrey Brace via vcf-midatlantic" < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
How would you explain the George Philbrick machine to an 8 year old? How do you explain what a vacuum tube actually does to an 8 year old?
On Sun, Nov 26, 2017 at 8:50 PM, Dave McGuire via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On 11/26/2017 04:54 PM, Jeffrey Brace via vcf-midatlantic wrote:
The parents love the explanation of the progression of technology. I need to learn more about how vacuum tube computers work to give them a comparison.
It's important to realize that there's really no difference. Vacuum tubes are analogous to FETs (field-effect transistors) and are simply the active switching element of tube-based digital computers, where transistors are the active switching element of solid-state computers. The logic...the instruction set, buses, etc...can be identical. The only real reason they're not is because computer architecture has grown up alongside, but largely independent of, electronics technology.
Now if you're talking about tube-based analog computers, that's a different animal...and the same point applies there. Analog computers are (mostly) composed of op-amps, and those op-amps can be built with tubes or transistors. (with or without multiple transistors being "integrated" into one "circuit", i.e. using integrated circuits) Again, the architecture is (or at least can be) the same.
The takeaway here is the importance of understanding the difference between architectures and implementations.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
On 11/26/2017 10:57 PM, william degnan via vcf-midatlantic wrote:
If a smart phone was full of tubes and associated 50's era components instead of today's smaller components the phone would have to be the size of Camp Evans.
Likely larger.
The MIT machine we have in the museum display is not anything like a cell phone however it's an analog computer sort of. Its more actually a bunch of Philco analog rack units that would have been part of a larger system plus a plotter and instruments generating "input". I have materials at my house that explain some of the rack components I promise next time I come up I'll try to put something together to explain what the MIT computer likely would have done. Also, as they are now the rack components are in a disorganized impractical configuration. We need to put them together into a more likely configuration asap. That would be a good thing to do next workshop. The process of researching the components will help expose it's function and help docents explain it.
If I'm not mistaken, that system is every bit a full-blown analog computer, by any reasonable definition. Remember, one can make a circuit that qualifies for that name with a few variable resistors, an op-amp, and a meter. Most every analog computer consists of a random bunch of separate circuits, usually multiple copies of each, and for the truly modular ones the number of each were specified at the time of purchase. If a scientist was working on a budget and he knew that most of his work could be completed on an analog machine with eight op-amps, he/she'd order the machine with eight op-amps. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
I think this would be good stuff to put on the docent wiki for future reference. On Mon, Nov 27, 2017 at 1:47 PM, Dave McGuire via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On 11/26/2017 10:57 PM, william degnan via vcf-midatlantic wrote:
If a smart phone was full of tubes and associated 50's era components instead of today's smaller components the phone would have to be the size of Camp Evans.
Likely larger.
The MIT machine we have in the museum display is not anything like a cell phone however it's an analog computer sort of. Its more actually a bunch of Philco analog rack units that would have been part of a larger system plus a plotter and instruments generating "input". I have materials at my house that explain some of the rack components I promise next time I come up I'll try to put something together to explain what the MIT computer likely would have done. Also, as they are now the rack components are in a disorganized impractical configuration. We need to put them together into a more likely configuration asap. That would be a good thing to do next workshop. The process of researching the components will help expose it's function and help docents explain it.
If I'm not mistaken, that system is every bit a full-blown analog computer, by any reasonable definition. Remember, one can make a circuit that qualifies for that name with a few variable resistors, an op-amp, and a meter. Most every analog computer consists of a random bunch of separate circuits, usually multiple copies of each, and for the truly modular ones the number of each were specified at the time of purchase. If a scientist was working on a budget and he knew that most of his work could be completed on an analog machine with eight op-amps, he/she'd order the machine with eight op-amps.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
On Sun, Nov 26, 2017 at 09:13:03PM -0500, Jeffrey Brace via vcf-midatlantic wrote:
How would you explain the George Philbrick machine to an 8 year old? How do you explain what a vacuum tube actually does to an 8 year old?
I'll jump in since I do have some interest in the education side though this isn't one of my better areas of expertise. Others will probably correct. I'm not sure how much of this you already know. I think the important thing to explain is the difference between an analog and digital computer. An analog computer is a type of computer that can be used to solve certain forms of mathematical equations. It predates the digital computer. It is not general purpose like modern digital computer. An analog computer is not capable of doing things like word processing or even keeping your bank balance. It became obsolete when digital computers became cheap and fast enough that the analog computer no longer had any advantage for solving its type of problems. It had a number of disadvantages such as needing to be wired up for each problem. We have an later transistorized analog computer that is being restored. If its on display the Philbrick is an earlier version of it same as the Bendix to other computers on display. Would require someone with more knowledge to truly compare the capabilities of the Philbrick vs another analog computer to determine how equivalent they are. The car suspension model is a common description of what could be used for. Your designing your car and want to tune the ride before you actually build it. http://www.analogmuseum.org/english/examples/vehicle_simulation/ I'll admit I'm not sure what an 8 year old can/wants to understand. I can comment on the tube vs transistor if you haven't gotten enough input.
I'll jump in since I do have some interest in the education side though this isn't one of my better areas of expertise. Others will probably correct.
Thanks for the for the explanation David! Let's start with the most common question that everyone asks: "How was this computer used?", "What could you do with this computer?", "What was it capable of doing?".
With the big Philbrick analog computer, I tell people how it's a bespoke system used as a teaching tool in the MIT mechanical engineering department from 1958-1970. The Bendiz G-15 was used in a civil engineering firm in the Baltimore area, the Univac was used at the Johns Hopkins U. Applied Physics Lab for developing software on the shipboard computers. I'm pretty sure this is covered in the info tablet kiosk for that part of the museum. :) On Nov 26, 2017 10:34 PM, "Jeffrey Brace via vcf-midatlantic" < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'll jump in since I do have some interest in the education side though this isn't one of my better areas of expertise. Others will probably correct.
Thanks for the for the explanation David! Let's start with the most common question that everyone asks: "How was this computer used?", "What could you do with this computer?", "What was it capable of doing?".
On 11/26/2017 10:48 PM, Evan Koblentz via vcf-midatlantic wrote:
With the big Philbrick analog computer, I tell people how it's a bespoke system used as a teaching tool in the MIT mechanical engineering department from 1958-1970.
Yeah but in the 50s/60s nearly every analog computer was "built" from a "menu" of possible components. There weren't many standard configurations for anything, because the type of problem to be solved directly and specifically dictated the circuitry required, unlike digital computers past a certain point. Suit yourself of course, but I'm not sure presenting it as a bespoke system really has any value, as all of them were. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
On Sun, Nov 26, 2017 at 10:34:27PM -0500, Jeffrey Brace via vcf-midatlantic wrote:
I'll jump in since I do have some interest in the education side though this isn't one of my better areas of expertise. Others will probably correct.
Thanks for the for the explanation David! Let's start with the most common question that everyone asks: "How was this computer used?", "What could you do with this computer?", "What was it capable of doing?".
I don't know enough history on either of the specific computers we have to comment on how they were used. I can only comment on the general class. Hopefully you can pull out what you need from this. The what was is capable of is solving systems of differential equations. Since since teaching calculus probably won't go over well just having the equations for some problem and saying the equations represents the example (bouncing ball, car spring & shock absorber etc) may be all that can be done. The complexity of equations that can be solved is limited by how many hardware block (integrators etc) the analog computer has. http://chalkdustmagazine.com/features/analogue-computing-fun-differential-eq... https://www.nsa.gov/news-features/declassified-documents/tech-journals/asset... The power is that many useful real processes can be transformed into that type of equations. Physical motion, chemical reactions, aircraft flight, The analog computer can solve the equations standalone by setting the initial conditions and then showing how they progress with time. For example the bouncing ball say you scaled 1V = 1 foot you start with 5V so ball dropped from 5 feet and can watch the height of the ball with time. You could also feed in an analog signal representing stimulus such as for the suspension example a signal representing the bumps in the road or for flight gusts etc perturbing the flight. Sometimes you just want the final state of the system so would let it progress until you get a stable answer and then read off the voltages and then convert them back to the original units. Other times you want to watch what happens over time. You can scale time also so the time "running" does not have to be equal to the physical problem. For viewing the time history an oscilloscope could be used and I think I remember a CRT in the Philbrick so it likely was used like an oscilloscope. It was said that our Philbrick had a plotter. That directly generates a hard copy graph of the value vs time. Some were chart recorders which can plot multiple values at once. Don't know what type we have. The analog computer my mother worked with modeled the flexural modes of vibration and critical frequencies of complex mechanical systems like ship hulls and shipboard machinery assemblies.
-----Original Message----- From: vcf-midatlantic [mailto:vcf-midatlantic- bounces@lists.vintagecomputerfederation.org] On Behalf Of David Gesswein via vcf-midatlantic Sent: 27 November 2017 12:55 To: Jeffrey Brace via vcf-midatlantic <vcf- midatlantic@lists.vintagecomputerfederation.org> Cc: David Gesswein <djg@pdp8online.com> Subject: Re: [vcf-midatlantic] vacuum tube computers, was Re: Museum Report 2017-11-26 November 26, 2017
On Sun, Nov 26, 2017 at 10:34:27PM -0500, Jeffrey Brace via vcf-midatlantic wrote:
I'll jump in since I do have some interest in the education side though this isn't one of my better areas of expertise. Others will probably correct.
Thanks for the for the explanation David! Let's start with the most common question that everyone asks: "How was this computer used?", "What could you do with this computer?", "What was it capable of doing?".
I don't know enough history on either of the specific computers we have to comment on how they were used. I can only comment on the general class.
Hopefully you can pull out what you need from this.
The what was is capable of is solving systems of differential equations. Since since teaching calculus probably won't go over well just having the equations for some problem and saying the equations represents the example (bouncing ball, car spring & shock absorber etc) may be all that can be done. The complexity of equations that can be solved is limited by how many hardware block (integrators etc) the analog computer has.
http://chalkdustmagazine.com/features/analogue-computing-fun- differential-equations/ https://www.nsa.gov/news-features/declassified-documents/tech- journals/assets/files/why-analog-computation.pdf
The power is that many useful real processes can be transformed into that type of equations. Physical motion, chemical reactions, aircraft flight,
The analog computer can solve the equations standalone by setting the initial conditions and then showing how they progress with time. For example the bouncing ball say you scaled 1V = 1 foot you start with 5V so ball dropped from 5 feet and can watch the height of the ball with time.
You could also feed in an analog signal representing stimulus such as for the suspension example a signal representing the bumps in the road or for flight gusts etc perturbing the flight.
Sometimes you just want the final state of the system so would let it progress until you get a stable answer and then read off the voltages and then convert them back to the original units. Other times you want to watch what happens over time. You can scale time also so the time "running" does not have to be equal to the physical problem. For viewing the time history an oscilloscope could be used and I think I remember a CRT in the Philbrick so it likely was used like an oscilloscope. It was said that our Philbrick had a plotter. That directly generates a hard copy graph of the value vs time. Some were chart recorders which can plot multiple values at once. Don't know what type we have.
The analog computer my mother worked with modeled the flexural modes of vibration and critical frequencies of complex mechanical systems like ship hulls and shipboard machinery assemblies.
Can I say that analog computers continued in use for a long time because they solve time domain problems in real time. (or sometimes in scaled real time, the speed of the solution can be increased when modelling long term processes, say glacial flow, or slowed down, e.g. for some problems involving nuclear collisions) This contrasts with digital solutions where the speed of calculation depends very much on the complexity of the equations. So for example the very popular SPICE program which models electronic circuits, essentially solves the same equations that an analog computer solves to calculate voltages and currents in a circuit over time. As it's a digital solver, it solves the equations at discrete points in time. As it evaluates the equations it estimates the error and if it finds large errors it will reduce the time step thus maintaining accuracy but increasing the solution time... An analog computer does not do this, making them popular for applications such as flight simulation, where, if the pilot performs a sudden actions, the last thing we need is to have to wait because the equations have become complex... Dave
I'll jump in here (I've been meaning to do this for a while). There is a TV channel, on cable, available in the Washington, DC area that broadcasts original unedited 1950's programs, including commercials. I have recorded and digitized several Sperry/Univac commercials from this channel, including some fairly long ones touting how the systems will benefit business. Also, some very early programmer/engineer want ads. They are digitized in MP4. Maybe they could be put on a loop and shown nearby? Bill S. -----Original Message----- From: vcf-midatlantic [mailto:vcf-midatlantic-bounces@lists.vintagecomputerfederation.org] On Behalf Of Jeffrey Brace via vcf-midatlantic Sent: Sunday, November 26, 2017 10:34 PM To: vcf-midatlantic Cc: Jeffrey Brace Subject: Re: [vcf-midatlantic] vacuum tube computers, was Re: Museum Report 2017-11-26 November 26, 2017
I'll jump in since I do have some interest in the education side though this isn't one of my better areas of expertise. Others will probably correct.
Thanks for the for the explanation David! Let's start with the most common question that everyone asks: "How was this computer used?", "What could you do with this computer?", "What was it capable of doing?". --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
I think it would be good to put some of them on the tablets. On Tue, Nov 28, 2017 at 12:12 PM William Sudbrink via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'll jump in here (I've been meaning to do this for a while). There is a TV channel, on cable, available in the Washington, DC area that broadcasts original unedited 1950's programs, including commercials. I have recorded and digitized several Sperry/Univac commercials from this channel, including some fairly long ones touting how the systems will benefit business. Also, some very early programmer/engineer want ads. They are digitized in MP4. Maybe they could be put on a loop and shown nearby?
Bill S.
-----Original Message----- From: vcf-midatlantic [mailto: vcf-midatlantic-bounces@lists.vintagecomputerfederation.org] On Behalf Of Jeffrey Brace via vcf-midatlantic Sent: Sunday, November 26, 2017 10:34 PM To: vcf-midatlantic Cc: Jeffrey Brace Subject: Re: [vcf-midatlantic] vacuum tube computers, was Re: Museum Report 2017-11-26 November 26, 2017
I'll jump in since I do have some interest in the education side though this isn't one of my better areas of expertise. Others will probably correct.
Thanks for the for the explanation David! Let's start with the most common question that everyone asks: "How was this computer used?", "What could you do with this computer?", "What was it capable of doing?".
--- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
On 11/26/2017 09:13 PM, Jeffrey Brace via vcf-midatlantic wrote:
How would you explain the George Philbrick machine to an 8 year old?
Well, as you know it's critically important to tune your presentation to the level of the guest. When starting a more personal tour of LSSM, we usually find a non-intrusive way, starting out with reading body language etc, to ask a person what their levels of technical knowledge and interest are. Then we explain things in different ways, on different levels, based on that. For a total technical neophyte, our explanations are more geared toward talking about how what we have now (holding up my smartphone) wouldn't exist without having first passed through all of these (gesturing toward the exhibit floor) phases of development, then go to some specific stories as to how and why. For an EE or CS person with a background in electronics and/or processor architecture, that's a waste of time. We go into things like "this machine is a 12-bit system implemented using all 7400-series TTL chips" when I fire up the PDP-8/e. I talk about "no chips at all, all discrete transistor logic" when we walk past the table of Straight-8s. While the LSSM doesn't have anything like the Philbrick system, we do have a Heath H-1, another late-1950s tube-based analog computer. To a young person, we'd explain that it was used by scientists and engineers to perform calculations for designing planes and big buildings. It's complicated, look at all those knobs! But to an EE/CS person who maybe doesn't know about analog computers (most haven't), we explain that it's a system with no bits, just voltages representing physical quantities, and most importantly it's not a discrete system, but a continuous system. These operational amplifiers (gesturing toward the op-amps) and resistors can be wired up to perform most any mathematical primitive, and wired together with capacitors to perform integration and differentiation, to solve the differential equations that most every real-world process is based on.
How do you explain what a vacuum tube actually does to an 8 year old?
I wouldn't, as there's essentially no chance that he/she would be interested or have the background to be able to understand it. See above. ;) -Dave -- Dave McGuire, AK4HZ New Kensington, PA
-----Original Message----- From: vcf-midatlantic [mailto:vcf-midatlantic- bounces@lists.vintagecomputerfederation.org] On Behalf Of Dave McGuire via vcf-midatlantic Sent: 27 November 2017 01:51 To: Jeffrey Brace via vcf-midatlantic <vcf- midatlantic@lists.vintagecomputerfederation.org> Cc: Dave McGuire <mcguire@neurotica.com> Subject: [vcf-midatlantic] vacuum tube computers, was Re: Museum Report 2017-11-26 November 26, 2017
On 11/26/2017 04:54 PM, Jeffrey Brace via vcf-midatlantic wrote:
The parents love the explanation of the progression of technology. I need to learn more about how vacuum tube computers work to give them a comparison.
It's important to realize that there's really no difference. Vacuum tubes are analogous to FETs (field-effect transistors) and are simply the active switching element of tube-based digital computers, where transistors are the active switching element of solid-state computers. The logic...the instruction set, buses, etc...can be identical. The only real reason they're not is because computer architecture has grown up alongside, but largely independent of, electronics technology.
Now if you're talking about tube-based analog computers, that's a different animal...and the same point applies there. Analog computers are (mostly) composed of op-amps, and those op-amps can be built with tubes or transistors. (with or without multiple transistors being "integrated" into one "circuit", i.e. using integrated circuits) Again, the architecture is (or at least can be) the same.
The takeaway here is the importance of understanding the difference between architectures and implementations.
So to take the simplest Valve computer, perhaps the Baby or SSEM that Kilburn and Williams built in Manchester, in architectural terms its architecture is pretty standard 32-bit words Single Accumulator Fixed instruction formats, one address, one op code Two quirks:- The conditional test only branches to "+1" or "+2" No ADD, only Load Negative, Subtract and store Its implantation is however unique or at least unusual to modern eyes in many places. The adder and subtractor are implemented as Kirchhoff analogue components. You can see the circuit of the subtractor here:- http://www.cs.man.ac.uk/CCS/SSEM/volunteers/subtractor.html as this allows the adder/subtractor to be built using fewer valves than an entirely digital line. In the same way several of the clock dividers use phantastron dividers http://www.cs.man.ac.uk/CCS/SSEM/volunteers/clock1x2split.html also described here:- http://www.radartutorial.eu/17.bauteile/bt52.en.html which were originally developed for Radar (Williams and Kilburn were Radar experts who built the Williams tube because they wanted to electronically process Radar Sign but again, analogue circuits adapted for digital use, probably because Kilburn and Williams were familiar with them, but also they used fewer valves that the equivalent digital circuits...
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
Dave G4UGM Manchester, England Now without gall bladder so may be able to get affordable travel insurance for USA
participants (8)
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Dave McGuire -
Dave Wade -
David Gesswein -
Drew Notarnicola -
Evan Koblentz -
Jeffrey Brace -
william degnan -
William Sudbrink