I'm trying to learn something about these old computers.  First of all, do they

actually follow program steps? I always equated the term computers with

something that can follow directions, calculate numbers, make decisions based on

the results.  How were these old computers used? Who used them? etc.

On Fri, Sep 07, 2012 at 11:50:32PM -0000, joshbensadon wrote:

> Are you saying the transistors in the old analog computers are robust?

> I haven't looked at part numbers yet, but they look like the old

> germanium TO-05 case style.

>

It wasn't intended to be that strong a statement. I don't have an analog

computer so don't have direct knowledge. From other electronics the lower

speed stuff tended to use transistors with breakdown voltages higher than

the supply. Also that a quick look assuming the parts are easily visible

will give you an idea of if overvoltage is likely to damage the unit. if

the breakdown voltage is somewhat higher than the preregulated voltage

then your unlikely to fry all the transistors if the supply looses

regulation.



> I'm trying to learn something about these old computers.  First of all,

> do they actually follow program steps? I always equated the term

> computers with something that can follow directions, calculate numbers,

> make decisions based on the results.  How were these old computers used?

> Who used them? etc.

>

I'm not that familiar with them.



They aren't computers in the modern sense. They simulate linear and

some nonlinear continuous time systems. They don't do steps and programming

is patch cables to wire the analog components in the correct configuration

for your problem and setting pots to set your coefficients. I think they

also had parts such as capacitors on plug in units to set the right values.

I think we have people on the list who have more knowledge than me who

hopefully will chime in.



Some promising links for info.

http://en.wikipedia.org/wiki/Analog_computer

http://ericarcher.net/devices/analog-computer-bouncing-ball/

http://courses.engr.illinois.edu/ece486/labs/lab1/analog_computer_manual.pdf

> -----Original Message-----

> From: midatlanticretro@yahoogroups.com

> [mailto:midatlanticretro@yahoogroups.com] On Behalf Of David Gesswein

> Sent: 08 September 2012 01:23

> To: midatlanticretro@yahoogroups.com

> Subject: Re: [midatlanticretro] Analog Computers - General description

>

>

> On Fri, Sep 07, 2012 at 11:50:32PM -0000, joshbensadon wrote:

> > Are you saying the transistors in the old analog computers

> are robust?

> > I haven't looked at part numbers yet, but they look like the old

> > germanium TO-05 case style.

> >

> It wasn't intended to be that strong a statement. I don't

> have an analog computer so don't have direct knowledge. From

> other electronics the lower speed stuff tended to use

> transistors with breakdown voltages higher than the supply.

> Also that a quick look assuming the parts are easily visible

> will give you an idea of if overvoltage is likely to damage

> the unit. if

> the breakdown voltage is somewhat higher than the

> preregulated voltage

> then your unlikely to fry all the transistors if the supply looses

> regulation.

>

> > I'm trying to learn something about these old computers.  First of

> > all,

> > do they actually follow program steps? I always equated the term

> > computers with something that can follow directions,

> calculate numbers,

> > make decisions based on the results.  How were these old

> computers used?

> > Who used them? etc.

> >



I have never used an analog computer in anger but I was taught to use them

as part of my Mathematics degree in 1972/3 and latterly I am part of the

team that maintains and demonstrates the Hartree Differential Analyzer at

the Museum of Science and Industry, Manchester England. If you have browser

other than IE you can see a flash video of the Hartree here:-



http://www.cs.man.ac.uk/~chl/hartree.html



I include this as the Hartree is a mechanical analog (analogue in the UK)

computer and a direct parent of the Electronic Analogue Computer. On the

Hartree we use the number degrees a shaft has turned to represent a variable

in our "program" , in an Analog Computer we use a voltage to represent a

variable.



The feature of what are vernally termed "analogue computers" (or

"differential analysers" in early references) is being able to "calculate"

the area under a curve, which mathematicians call "integration". This might

not seem a very useful thing to do, but in fact this ability will be needed

to solve a wide range mathematical problems involving "time".



At a simple level if we have a graph of say the speed of a car, and plot

this, then the area under the curve will give the distance travelled. If we

have a graph of acceleration then the area under that is speed. So if we

have two "integrators" then from acceleration we can calculate speed and

distance. This becomes interesting when we have equations that connects

these together. So if you fire a projectile (much nicer word than shell)

from a gun and you know the angle of the gun, the initial velocity of the

shell, the mass of the shell and its coefficient of drag then using Newton's

Laws of motion we can develop equations that link these together. These are

called differential equations. We can then set up a "program" on our analog

computer than shows where the shell is at any point in time. Of course

usually we are only interested in where it actually lands, but if we include

air resistance in the equations we typically need to do the whole

calculation to figure this out. Historically this calculation is what drove

analogue computer design and development.



So as part of its commissioning testing the Hartree was used to simulate

coal consumption in Railway Engines (I am told Hartree was a bit of a Steam

nut), calculate cooling rates in steel ingots, simulate noise in

transmission lines and model the stability of aircraft. Of course the

driving force behind the initial development of all this stuff is gunnery

calculations.



The plug in capacitors mentioned below are what perform the integration, the

amount of charge stored in these capacitors represents the area. For a low

voltage it will charge slowly, for a higher voltage more quickly. There are

high gain circuits (operational amplifiers) around the capacitor so its

charge doesn't dissipate. They are often on plug ins and switchable as

changing the values of the cap allows the program to run at different

speeds. For a problem such as the cooling of an ingot, we probably don't

want to wait several hours for our program to run, so we speed it up by

using smaller capacitors which charge more slowly. For problems like noise

in transmission lines where we are dealing in pulses travelling at close to

the speed of light then we will have to slow things down a bit. If we are

using one as part of an aircraft simulator for training pilots then

essentially we want real time.



They were widely used as they were much cheaper to make than a digital

computer and they could solve the problems in real time. In 1972 at college

we had three commercial analogue computers and I think 12 or 14 constructed

by the lab technicians.





> I'm not that familiar with them.

>

> They aren't computers in the modern sense. They simulate

> linear and some nonlinear continuous time systems. They don't

> do steps and programming is patch cables to wire the analog

> components in the correct configuration for your problem and

> setting pots to set your coefficients. I think they also had

> parts such as capacitors on plug in units to set the right

> values. I think we have people on the list who have more

> knowledge than me who

> hopefully will chime in.

>

> Some promising links for info.

> http://en.wikipedia.org/wiki/Analog_computer

> http://ericarcher.net/devices/analog-computer-bouncing-ball/

> http://courses.engr.illinois.edu/ece486/labs/lab1/analog_compu

ter_manual.pdf





Dave Wade G4UGM

Illegitimi Non Carborundum

--- In midatlanticretro@yahoogroups.com, "Dave" <dave.g4ugm@...> wrote:

>

> I have never used an analog computer in anger but I was taught to use them

> as part of my Mathematics degree in 1972/3 and latterly I am part of the

> team that maintains and demonstrates the Hartree Differential Analyzer at

> the Museum of Science and Industry, Manchester England. If you have browser

> other than IE you can see a flash video of the Hartree here:-

>

> http://www.cs.man.ac.uk/~chl/hartree.html

>



I'm really pleased, as an engineers of the 1970's, to see a brief presentation

of mechanical analog (differential) computers in the MARCH discussion. This is

truly "lost technology" by my standards and I'm glad it's getting support in the

UK.



To answer the original question, about the nature and use of electronic analog

computing. If you are interested enough, obtain some books on the subject from

the era. Many engineering books about analog computing are available cheaply

from Amazon - cheaper than those books on eBay that aren't listed by title, in

order to sell them at higher prices. In addition, you can get many of those same

books by loan through your local library, from university collections. That

service is called "interlibrary loan" and you can talk to your local library

about that service.



While it's fun to talk about these things and discuss questions and answers thru

email - it's more PRODUCTIVE to do the homework of reading the available

literature, and that means paper books.  They won't be available for many years

longer; that's another discussion. They were designed to explain the use of

these analog computers, to people would use them "in anger" as the poster

described. You will need to understand differential equations, just as any

binary programmer of microcomputers needs to understand Boolean logic and binary

arithmetic.



But differential equations STILL describe processes and model systems, from

chemical to economic, that are still modeled today. These machines can STILL do

some "work" that means something. They won't play Adventure, but you can have an

adventure in learning about and using them.



Herb Johnson

retrotechnology.com

On Sat, 8 Sep 2012, s100doctor wrote:



> To answer the original question, about the nature and use of electronic

> analog computing. If you are interested enough, obtain some books on the

> subject from the era. Many engineering books about analog computing are

> available cheaply from Amazon - cheaper than those books on eBay that

> aren't listed by title, in order to sell them at higher prices. In

> addition, you can get many of those same books by loan through your

> local library, from university collections. That service is called

> "interlibrary loan" and you can talk to your local library about that

> service.



     You might start with "The Handbook of Analog Computation":



http://www.analogmuseum.org/library/eai_handbook.pdf



     Also on that page are dozens of manuals, handbooks, tutorials and

lectures about analog computing:



http://www.analogmuseum.org/english/library.html





Mike Loewen 		 mloewen@...

Old Technology       http://sturgeon.css.psu.edu/~mloewen/Oldtech/

--- In midatlanticretro@yahoogroups.com, Mike Loewen <mloewen@...> wrote:

>

>     You might start with "The Handbook of Analog Computation":

>

> http://www.analogmuseum.org/library/eai_handbook.pdf

>

>     Also on that page are dozens of manuals, handbooks, tutorials and

> lectures about analog computing:

>

> http://www.analogmuseum.org/english/library.html

>

>

> Mike Loewen 		 mloewen@...





Mike, Thanks! That's a great place to start.  As usual, I have much homework to

do... so I'll be here in the corner, quietly reading if anyone wants me.



I'm going to search around that site to see if they might even have schematics

for this EAI computer.



Cheers!

Josh

--- In midatlanticretro@yahoogroups.com, "s100doctor" <hjohnson@...> wrote:

> To answer the original question, about the nature and use of electronic analog

computing. If you are interested enough, obtain some books on the subject from

the era. Many engineering books about analog computing are available cheaply

from Amazon - cheaper than



Thanks Herb,



Your good words are always a welcomed sight.

Yes, I have much reading to do.  The online book referenced by Mike appears to

be a real gem, especially since this Analog Computer is an EAI model.  I did a

search for "Analog Computer" on Amazon and got 3,000+ hits.  Can you help me out

with a known title?



Further, would you know if schematics can be found for these old computers,

sorry I don't have the exact model number.  If you do have these schematics in

your collection, please name your price.



Cheers,

Josh

--- In midatlanticretro@yahoogroups.com, joshbensadon  wrote:

>



> Thanks Herb,

>

> Your good words are always a welcomed sight.

> Yes, I have much reading to do.  The online book referenced by Mike appears to

be a real gem, especially since this Analog Computer is an EAI model.  I did a

search for "Analog Computer" on Amazon and got 3,000+ hits.  Can you help me out

with a known title?

>

> Further, would you know if schematics can be found for these old computers,

sorry I don't have the exact model number.  If you do have these schematics in

your collection, please name your price.

>

> Cheers,

> Josh



I just saw your message, about two weeks after you posted it.



Contact me privately, if you want specific things from me, Josh. I don't read

this MARCH list on any regular basis, or engage in long discussions on it in

general. That's simply not what I do, why that may be is not particularly

relevant except to say it's nothing to do with you.



Also, I can't follow exactly what schematics you are looking for, and how on the

one hand you have some kind of EAI computer, but on the other hand don't know

what model it is.



I'm sorry you find the learning situation about them, to be complicated and with

an unclear path. That's the nature of technology which is obsolete, generally

used only by scientists and specialists, and largely documented only in books

from the period. And from a period before personal computers and digital

networking of any kind - not that most of that would help.



Since I'm of that obsolete and ancient time, and I was an engineer, I know

something about it. But not something I can point to easily, that's in one book,

or that can be learned by reading one or two books.



Sorry, but that's not my fault. It's old, it's complicated, it involves

knowledge about things. Without that knowledge, operating an analog computer

will make no sense at all, and seeing it run will be incomprehensible. It was

difficult at the time, that knowledge is still difficult today. I can't

reasonably think of an easy way to get around those circumstances - either about

the background knowledge needed, or the operational knowledge to use such

things, as they are almost IDENTICAL - and entirely unlike personal computing

today.



herb

--- In midatlanticretro@yahoogroups.com, "s100doctor" <hjohnson@...> wrote:

>

> Also, I can't follow exactly what schematics you are looking for, and how on

the one hand you have some kind of EAI computer, but on the other hand don't

know what model it is.

>



Please let me explain.  It's not my computer, but it belongs to the York

Univeristy Museum operated by Zbigniew Stachniak.  I only get to work on this

machine once a week or every two weeks, and I didn't get to see the exact model

of it.  Zbigniew told me the model number last week, but my lack of short term

memory strikes again.



I'm not in any rush to learn all about it, I'll just take my time and enjoy the

ride.  I've already found some information online (thanks to the posts in this

group).



PS. My contact with Zbigniew should also be credited to Bill and Evan's Hope

presentation.  I live 10 minutes from York and have been visiting the campus for

years but have never known about their Vintage Computer Museum until now.



Cheers,

Josh

>>> My contact with Zbigniew should also be credited to Bill and Evan's Hope

presentation. I live 10 minutes from York and have been visiting the campus for

years but have never known about their Vintage Computer Museum until now.



Awesome. Tell Zig I said hello.

> >

>

> Please let me explain.  It's not my computer, but it belongs to the York

Univeristy Museum operated by Zbigniew Stachniak.  I





York, PA?



>

> PS. My contact with Zbigniew should also be credited to Bill and Evan's

Hope presentation.  I live 10 minutes from York and have been visiting the

campus for years but have never known about their Vintage Computer Museum

until now.

>



I live kind of close and would be interested to drive out some time to

check it out.



http://www.cse.yorku.ca/museum/



What's actually on display there?



Bill

--- In midatlanticretro@yahoogroups.com, "B. Degnan" <billdeg@...> wrote:

> York Univeristy Museum operated by Zbigniew Stachniak.  I

>

>

> York, PA?

>



No, York University in Toronto, Ontario.



> What's actually on display there?

>





I'm a newbie at old computers, so I'll probably miss a few key systems.

I think Zbigniew's favorite is the MCM 70 computer, he wrote a whole book on it.

There are lots of other systems as you saw in the web link you provided, but I'm

not sure what's worth mentioning?  Dynalogic systems?  There's some of the the

more familiar common systems, but several word processors and obsure ones I

don't remember the names of.  But there is a whole line of MCM computers.  These

were based on the 8008 and when that processor became too slow, they went the

way of emulating the processor with faster logic chips so they wouldn't have to

re-write software.



Anytime you're in Toronto, I'd be happy to show you around.



Cheers,

Josh

>> York, PA?



Toronto, Canada.

 

I'm trying to learn something about these old computers. First of all, do they actually follow program steps? I always equated the term computers with something that can follow directions, calculate numbers, make decisions based on the results. How were these old computers used? Who used them? etc.

On 9/7/2012 7:50 PM, joshbensadon wrote:

>I'm trying to learn something about these old computers. First of all, do they

actually follow program steps? I always equated the term computers with

something that can follow directions, calculate numbers, make decisions based on

the results. How were these old computers used? Who used them? etc.



I just happened to have discovered this great video a couple of days ago.  It's

a 50's US Navy instructional film about the mechanical computers they used. 

It's really eye-opening and very high quality.  (It gets to the meat about two

minutes in.)  For me, it demonstrated the analog/mathematical approach, in

contrast to the digital/logical approach I grew up learning.

http://www.youtube.com/watch?v=s1i-dnAH9Y4



- Ken

--- In midatlanticretro@yahoogroups.com, Ken <kenzolist@...> wrote:



> I just happened to have discovered this great video a couple of days ago. 

It's a 50's US Navy instructional film about the mechanical computers they used.

It's really eye-opening and very high quality.  (It gets to the meat about two

minutes in.)  For me, it demonstrated the analog/mathematical approach, in

contrast to the digital/logical approach I grew up learning.

> http://www.youtube.com/watch?v=s1i-dnAH9Y4

>

> - Ken

>

http://www.eugeneleeslover.com/VIDEOS/fire_control_computer_1.html



It looks like the site linked above is a primary Web source for WWII and later

Naval fire control computer documents. It may be the original source for the

video referenced above, or certainly an earlier one.



These control computers used rotational position (radius vs angle) as means of

expressing an analog function. One input variable was a cam on a shaft; two

input variables was a surface on a cylinder. By cascading, you could have

several variables per output. The video series shows this, and the Navy

textbooks on the site above explain further.



Mechanical computers like this were "programmed" by manufacture; one design

equals one program. Electronic analog computers were programmed by wiring panels

and adjusting components, as well as by design or by hard-wire. Hybrid analog

computers, made the connections and adjustments digitally.



I knew nothing about the above, until I did some Web searching based on the

reference first given. It's good to see more ancient technology on the Web. In

this case, advanced WW II technology, digitized from books and films.



Herb Johnson

> http://www.eugeneleeslover.com/VIDEOS/fire_control_computer_1.html

>

> It looks like the site linked above is a primary Web source for WWII and

> later Naval fire control computer documents. It may be the original source

> for the video referenced above, or certainly an earlier one.



I think some of these are originally from the Historic Naval Ships

Association. There is a group of us ship geeks that are also trying to

save and archive the technology, bitsavers style.



> These control computers used rotational position (radius vs angle) as

> means of expressing an analog function. One input variable was a cam on a

> shaft; two input variables was a surface on a cylinder. By cascading, you

> could have several variables per output.



There is also a class of fire control computers that used linear

displacement of levers and linkages, rather than rotation. These

machines were much cheaper to make, but not quite as accurate. And of

course, there were hybrids of all sorts. I had a small collecton of

small machines and assemblies at VFC East number 2.



Trivia - there are two Mk 4 Torpedo Data Computers still in active

service, in the Taiwan Navy. They have been in near continuous service

since 1946.



--

Will