Old calculator with reverb ram

[Tugdual]

How a spring reverb becomes a memory for a calculator

https://youtu.be/2BIx2x-Q2fE

[jebem]

Very nice find.
Delay line memories were common in the 60's, before integrated circuits were invented by Texas, as a cheaper and smaller size alternative to use flip-flop circuits that would take at least two huge sized germanium transistors per each memory bit cell.

Probably the first ever RPN electronic calculator?

[Gerson W. Barbosa]

(12-01-2017 04:33 PM)jebem Wrote:  Very nice find.

Agreed!

The overenthusiastic guy reminds me of Doc Brown in Back to the Future :-)

I can only imagine what it was like using one back in the day!

By using repeated square root, one could even compute logarithms. For instance, the natural logarithm of 2 can be computed with 6 or 7 correct decimal places on it, I would guess.

Gerson.

[PANAMATIK]

(12-01-2017 06:45 PM)Gerson W. Barbosa Wrote:  The overenthusiastic guy reminds me of Doc Brown in Back to the Future :-)

Gerson.

This overenthusiastic guy is Clifford Stoll, the author of "The Cuckoos Egg". BTW he also owns an HP-25E calculator.

Bernhard

[Joe Horn]

Aha! Now I know why "The Cuckoo's Egg" was such a delightful read! That guy is a HOOT! Thanks for sharing his video with us, Tugdual!

EDIT: Ohmygosh, this guy is amazing. He makes and sells glass Klein bottles! My favorite is the Klein Stein, a real glass drinking mug which is also a Klein bottle! (Well, to be precise, a 2-dimensional manifold existing in 4 dimensions but immersed in 3 dimensions). His entire Acme Klein Bottle website is hilarious.

[pier4r]

I recommend to follow numberphile on youtube every now and then. It is pretty interesting input.

[striegel]

(12-02-2017 02:17 AM)Joe Horn Wrote:  ...He makes and sells glass Klein bottles! My favorite is the Klein Stein, a real glass drinking mug which is also a Klein bottle!
...

What a great gift idea - and just in time for Christmas! Thank you, Joe.

[PANAMATIK]

(12-02-2017 03:34 PM)striegel Wrote:  

(12-02-2017 02:17 AM)Joe Horn Wrote:  ...He makes and sells glass Klein bottles! My favorite is the Klein Stein, a real glass drinking mug which is also a Klein bottle!
...

What a great gift idea - and just in time for Christmas! Thank you, Joe.

I have got already a Klein Bottle and Klein Stein from him, they are really nice gadgets, in exchange for a special "Kleinbottle HP-25E" calculator, which I programmed for fun to show and calculate numbers in reverse order. He actually very much liked it.

Bernhard

[BobVA]

(12-02-2017 02:17 AM)Joe Horn Wrote:  EDIT: Ohmygosh, this guy is amazing. He makes and sells glass Klein bottles!.

Entertaining video of his home-built robot forklift to warehouse them in the crawlspace under his house.

[Steve Simpkin]

Very cool! I am always amazed throughout history at what engineers could do with the technology that was available at the time.
More information on the Friden EC-130 (1964) and 132 (1965) calculators:
http://www.oldcalculatormuseum.com/friden130.html
http://www.oldcalculatormuseum.com/friden132.html

1965 was a very interesting year for electronic calculators that saw several breakthroughs in technology.

There was the Toshiba BC-1441 Electronic calculator that used discrete capacitors to form an early type of the Dynamic memory that is used for RAM in all modern computers, phones, tablets, etc. Just like today's SDRAM, each capacitor had to be periodically "refreshed" to keep its charge (or lack of charge) for storage of its one bit.

More importantly, 1965 also saw the introduction of the Victor 3900, the first calculator (or any type of consumer device) to use Large Scale Integration Metal Oxide Semiconductor (LSI MOS) integrated circuits for all of the logic of the machine. This was a true milestone in technology that helped pushed forward the upcoming microprocessor revolution.
http://www.oldcalculatormuseum.com/d-victor3900.html

Calculator History Timeline:
http://www.oldcalculatormuseum.com/timeline.html

[jebem]

(12-01-2017 06:45 PM)Gerson W. Barbosa Wrote:  By using repeated square root, one could even compute logarithms. For instance, the natural logarithm of 2 can be computed with 6 or 7 correct decimal places on it, I would guess.

Gerson.

Are you referring to the Briggs works that i presume were also used in the HP-35 as the base to calculate logarithms?

My math knowledge is very rusty to be able to fully understand Briggs work, although I enjoy reading and learning when I have spare time to so so.

[Gerson W. Barbosa]

(12-03-2017 12:34 PM)jebem Wrote:  

(12-01-2017 06:45 PM)Gerson W. Barbosa Wrote:  By using repeated square root, one could even compute logarithms. For instance, the natural logarithm of 2 can be computed with 6 or 7 correct decimal places on it, I would guess.

Gerson.

Are you referring to the Briggs works that i presume were also used in the HP-35 as the base to calculate logarithms?

Olá, José!

I’m using a small improvement for better accuracy I made to an old algorithm based on repeated square root extraction, as described here:

http://www.hpmuseum.org/forum/thread-5907.html

Here is an estimation of ln(2) on a 12-digit RPN calculator using this method:


2
√ -> 1.41421356237
√ -> 1.18920711500
√ -> 1.09050773266
√ -> 1.04427378242
√ -> 1.02189714865
√ -> 1.01088928605
√ -> 1.00542990111
√ -> 1.00271127505
√ -> 1.00135471989
√ -> 1.00067713069
√ -> 1.00033850805
√ -> 1.00016923970 (*)
2 * -> 2.00033847940
1 - -> 1.00033847940
√ -> 1.00016922538
1 - -> 0.00016922538
4096 x -> 0.693147156480

PS.:

(*) For best accuracy, keep pressing the √ key until you get a result close to 1.0001 (or 0.9999, for arguments less than 1), as in this example. The final multiplication constant will be 2^n, where n is the number of the successive square root operations. In this case n = 12, hence 4096 (2^12).

This might have been useful 50 years ago :-)

[StephenG1CMZ]

Great video Tugdual, thanks for sharing it.

It amazes me what could be accomplished with a handful of bits back then...
Its even more amazing than a 64GB Android crashing claiming that it doesn't have enough bits now.

[Dave Britten]

(12-01-2017 06:45 PM)Gerson W. Barbosa Wrote:  The overenthusiastic guy reminds me of Doc Brown in Back to the Future :-)

Doc Brown mixed with Tigger from Winnie The Pooh.

Very interesting video. I certainly never would have expected to see piano wire used as RAM.

[Paul Berger (Canada)]

Delay line memory was very common, I worked on machine built in the 60s, before solid state memory, where delay line memory was used because core would have been too expensive. You may remember the filling out answers to standardized tests on on an IBM form that was a 8.5x11 sheet with boxes you filled in with a pencil, well I worked on one of the machines that marked those sheets. The answers where read in from a master sheet and stored in a delay line and then compared to the student sheets. I worked on the advanced model that read the sheets optically, an earlier version had metal finger that rode along the page and detected the conductive graphite marks on the page.