Digital Slide Rule?

Sound cool. You need a lawyer.

Damn I need to get back to work on my electric harmonica... Don't tell, Don't tell.

Never mind, already done it! Have two patents, too.

Title of the first is: " a means to synthetically reproduce actual sound vibrations emanating from a harmonica reed by means of an electronic sensing and digital reproducing device and amplifier/loudspeaker.

Title of the second is," a means of support for a means to synthetically reproduce actual sound vibrations emanating from a harmonica reed by means of an electronic sensing and digital reproducing device and amplifier/loudspeaker.

I'm working on the wireless model now. Won't need the stand for that one, maybe.

Maybe I'll patent a hands free stand for unamplified harmonicas. There has to be a market for that. I've never seen one, have you?

If you did that it would spoil an old joke. An engineer used to be defined as someone who multiplies 2x2 on a slide rule and gets 3.99, and rounds it off to 4 for convenience.

I still have my full size and a pocket version, about 4" long.

Me too. Also have a small pocket model Pickett slide rule mounted in a frame with a sign that says "In case of computational emergency break glass" hanging in my office. Identifies me with the dinosaurs.

What about a graphic slide rule on you PC's monitor? Move the sliding stuff around with your mouse, then you can zoom in on those cute, little, no good, God damn, mother&%$*ing, frustrating lines!!!

Hi Vermin,

Try http://www.finseth.com/realbasic/index-sliderule.php and you can have it in Linux, Mac and Windows - bit of a hoot and it works

Software in RealBasic - and the Odessa Trojan.

I bought my digital slide rule in the 1970's (HP35).

Soon after the HP45 replaced all need of a slide rule.

A slide rule was actually a wonderful machine -

Examples :

Move the slide and the cursor and you have the volume of a round reservoir.

Move the cursor and the slide and you have the radius of a specific area circle.

At one stage I even made (print) slide rules on laminated cardboard for use by sales.

Example : friction loss in irrigation lateral from pipe size, number , spacing & delivery of emitters.

Break up into small pieces, apply flame, keep warm for a few minutes... Remain warm by basking in the afterglow of the slide rule's demise.

Take it you weren't fond of slide rules, then?

Just saw them for a second as the HP calculators came in. I have 8mm film of all the Engineering students with tears of joy in their eyes.

and then you can go to your Hi Tech HP-35.

http://www.hpmuseum.org/simulate/hp35sim/calc.html

Which was the HP (HP65?) which had the programmable strip ?

I think the 45 had a strip. Nostalgic man!!

I had a TI (Texas Instrument) 65 (i think) with a strip and a ROM module.

My HP favourite was the HP71 (worked in Rocky Mountain Basic)

Wouldn't work with my Pickett, although you could make soda cans out of it.

I didn't buy the first HPs, they were too expensive, I started with the TI, SR-50. That way, I didn't have to learn "Reverse Polish" notation, although when I did learn it later, it made good sense.

Lynlynch -- Do your market research first before you invest in this venture. Real simple. Count the number of serious slide rule collectors. That will be your market. That's it.

Ed Weldon

I don't think a digital slide rule will sell very well. Todays students are into graphing calculators, etc. I remember using my slide rule but unless I am mistaken, and I might be, I don't remember being able to subtract and/or add with it. It's an interesting idea and I would probably buy one to try it out, providing the cost isn't to great. It would be fun to play with, kind of like a new toy for use folks past 70. In todays world, the students in science and math are farther ahead with their hand held mini-computers.

I don't remember being able to subtract and/or add with it.

There! You've hit upon the justification for the digital slide rule. As you may know, slide rules multiply by adding logs. So adding should be a simple matter of changing the log scale back to a linear scale... which could be done reasonably easily if the entire slide rule were in fact a video screen. In the interests of making things complex, this would best be done calculating the correct positions of the lines (using the device's display calculation subsystem) rather than something simple like having two graphic presentations stored in memory for display.

Then we'd have all the disadvantages of a slide rule combined with all the disadvantages of electronic devices.

To further increase complexity and desirability, we could replace the linear position transducers of the basic model (used to sense slide position) with a miniature inertial navigation system, which would instead calculate the position of the slide by integrating over time all the acceleration vectors to which the slide is subjected. GPS would be used in conjunction with this system to help ensure that the inner and outer slides are positioned in the same county.

The comparison that comes immediately to mind is a digital multimeter and an analog meter. The digital meter is superior for determining a stable voltage but the analog meter is better for a changing voltage ( as in "peaking" an adjustment). To carry that concept further, simulation packages (SPICE) are better for static values than changing values. They can be dealt with, but are not inherently part of the simulation. It takes something like a Bode plot to do that type of analysis.

A slide rule is an analog device and may point to an easier way to handle some calculations like that.

No, you are not crazy.

Already been done. Virtually any scientific calculator, even an el cheapo model, is essentially the equivalent of a digital slide rule, and often more. (In a way, this is sad. I used to know every function of a log-log/trig slide rule, having won two as prizes in mathematics contests. But if you asked me today, I wouldn't easily be able to describe the process. After all, when you can embed a Moody chart with interpolation into a spreadsheet, and calculate pipe flow problems with a few keystroke entries, the once dearly loved antique rather loses its luster.) Sigh--but Hallelujah!

I think that most users would be shocked to find out that engineers were able to design cars and bridges and skyscrapers working with three significant digits (maybe four for the giant meter long versions). I assume that the atomic bomb was designed by slide rule. The slide rule was a great numeric processor, but had a pretty lame user interface. I really like my newfangled HP 15C.

Slide rules and three significant digits worked most of the time in the old days; but I recall the production engineering group at one place I worked having to use 4 and sometimes 5 place log tables for some precision machining calculations. Then there was the cost estimator at another place where I worked in the early 60's. He was the only guy in the engineering office that had a Freiden mechanical calculator.

Ed Weldon

The Frieden and Monroe (?) mechanical calculators were way out of an engineering students price range, but one guy in the fraternity did have a Curta calculator.

One day back in 1968 (?) I was rummaging around in the back rooms of the physics building, I found a Wang (?) electornic calculator. It was 8-12 inches across and had nixie tubes for the display. It was 4 function, add, subtract, multiply, and divide. The calculator had a 1" cable going from it to an attache case sized box on the floor. It had to be all discrete components. Bet it cost more than my tuition.

All the ?s are because I've contracted a mutant west nile virus called the sea nile virus.

Wang!! I used one of those, exactly as described, in engineering school. As you wrote, it was only a four banger, incapable of even doing a square root, if I remember correctly.

I too, have been increasing affected by the sea nile virus.

It's called a calculator.

I used to be in the "Slide Rule Club" in the mid-60's. Went to meets, etc. Many years later when I asked the teacher in high-school who taught slide rule and handled the club how that was going, he told me it was no longer the slide rule club, but the calculator club. Seems they did away with the slide rules and just substituted calculators. Of course, it's not the same. With a calculator you don't have to keep track of decimal places in your head.