I Am The Computer Now - Friden STW10 Mechanical Calculator

Pocket calculators are almost extinct now that we carry around mini-computers, but what were accountants and engineers using for complicated math before them? Come take a look at the Friden STW10 a local fan loaned us.

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MUSIC CREDIT
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Title: Laszlo - Supernova

CHAPTERS
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0:00 Intro
1:05 Calculators
2:05 Friden STW10
4:27 Number Crunching
8:20 Square Root
11:41 Conclusion
13:32 Outro

[sheepco]

Obviously Riley is always a phenomenal host, but man, the set and b rolls, all around cinematography and production, was the best ive ever seen in an LTT video. Very nice work all around.

[sethstarrett]

Big fan of the quarterly "Professor Riley" videos. This historical context from a mainstream source is incredibly important.

[aidanstarke]

This literally topped all other LTT videos the writing was good the camera work. Clearly people were knowledgable about the topic and the genuine enthusiasm was contagious

[ShukenFlash]

I love Friden calculators, there's just something so satisfying about them. This is one of the best LTT videos I've seen in a long time. The cinematography, B roll, lighting, everything was turned up to 11. Would love to see more of these little documentaries.

[WickedGamerCollector]

What an amazing piece of tech from back in the day 😄

[Lysus]

8:16 for those of you wondering, 10's complement is a way of representing decimal numbers as a negative without using a negative sign. So mechanical or even digital calculators can't just use a negative sign and automatically know it's a negative value and doesn't differentiate the numbers for example 54 from its negative. (Also edit at the bottom explaining a bit of 2's comp and how it's used in modern computers sort of)
To get around this, complements are used (this is common in modern computers with 2's complement in binary). This is a different method of representing a negative number without the negative sign.
This is done because number X and it's negative -X have a special property. That is that if you add X + -X it equals 0. So let's use 54 again. 54 + -54 = 0 But what if we can replace -54 with a positive number that still gets us 0. Normally this isn't possible but we can mess around with it a bit. So first say 54 + -54 is actually equal to 00 (two digits specifically). If we do this we can actually fake a 00 by using 100 instead. So we need to replace -54 with a number that satisfies 54 + C = 100 (C = complement). So we just do 100 - 54 and we get 46. 46 is the 10's complement of 54.
Now let's practically do this. Let's do 78 - 54. So normal subtraction will give us 24.
Now let's use 10's comp. 78 + -54 but we can now replace -54 with positive 46 so we get 78 + 46. This is equal to 124
So the 2 answers we have are 24 and 124. But for the 10s comp equation, we restrict ourselves to the first to digits so instead of 124, we actually have 24 with a 1 in front of it. this is how 10's comp works. So what do we do with the 1 then? The 1 is what is called the sign digit. This value indicates if the number is in normal decimal (positive) or in 10's comp form (negative).
If we did a subtraction problem that gives a negative answer like 20 - 54 which is normally equal to -34 and use 10's comp we get 20 + 46 which is 66. However 66 can be read as 0 66, 0 representing that the number is in 10's comp (negative). To solve that we need to apply 10's complement to it. To do this we do 100 - 066 which = 34 hence it is -34.
Hopefully that helped explain this. Thought I'd mention it cause Riley said 10's comp lol.

EDIT: Grammar. Also an explanation of 2's complement in binary which is what modern computers and calculators use.

2's complement
So nowadays, 10's comp isn't used as much anymore but 2's comp is. 2's comp is the method of getting "negative" numbers in Binary. 2 meaning base 2.
So the concept is entirely the same where you get a number for example 101 (5 in binary) and getting it's complement by finding a number that adds to it and gets you 000 with a 1 in front. In the case of 101 it is 011 (3 in binary). So -101 = 011 (in 2's complement).
So let's try using this in an equation. 111 (7) - 101 (5). Normally the answer to this is 010 (2). But let's use complements. So we already have the 2's comp of 101 so the equation is now 111 + 011 which is equal to 1010 and same as with 10's comp. We only focus on the last 3 bits (binary digits) and we have 010 with a 1 in front indicating it's sign. But what happens if we get a negative answer.
Let's do 011 (3) - 101 (5) which is normally - 010 but now let's do it with 2's comp. 011 + 011 and this gives us 0110. however if we look at the last 3 bits and separate the sign it's 110 with a 0 indicating it's in 2's complement form so we need to reapply the algorithm. To do this we do 1000 - 0110 and that gives us 0010 or 010 that which is the same as the initial answer.

(how 2's comp is applied in computers)
So the way this is applied to computer systems is actually not the same as described above. So the normal algorithm for 2's or any base's comp is 1 followed by a set number of 0s. But in computer systems we are locked to a set number of bits in the system. so let's use a 4 bit system. We have to do all calculations in 4 bits which puts a limitation on 2's comp. This is that we can't use 10000 which is 5 bits. So if we tried doing the 2's comp of 1001 (9) we can't do 10000 - 1001.
To get around this limitation we actually split up the 10000 into 1111 + 1 allowing us to work in 4 bits (or whatever bits we need). This means we do 1111 - 1001 (9) + 1 instead.
Now if we look at the first section 1111 - 1001 (9), this gives us 0110. This actually gives us the inverse of 1001. so if we look carefully 1001 inverted is 0110. Hence the first step in 2's comp is invert. Then we add 1
Inversion can also be looked as the logical operation XOR where one input is always going to be 1 while the other is the number we're finding the complement for. This then can be used by a 4 bit system to do subtraction.

[randomgeocacher]

Extremely cinematic lighting etc. and the presentation is incredible. Feels like LTT went above and beyond to make this oldie shine!

[oozerderp]

It blows my mind that computing power had come so far. Charging control boards are more powerful than the computers that Apollo 11 used

[AustiuNoMatterWho]

This is probably the most aesthetically please LTT video I have seen in a while. Really feels nice and Riley just puts it all together so nicely for a topic like this one

[johnboleyjr.]

The absolute eloquence, and sheer brute force determination of mankind to make it work, is why I absolutely love electromechanical, and mechanical mechanisms such as this. If you want to be impressed, take a look inside of a jukebox, or an autoloading record player. At first it all seems like chaos, until you start breaking it down to the simple systems that make it all happen, usually some form of an "on/off" switch. Typically they all work together in some mesmerizing ballet of cogs, wheels, levers, springs, etc..., most of the time orchestrated by a single motor. I'm pretty sure this calculator runs off of one single motor. Astounding.

[nulla]

LTTDiscovery channel. This is quite intriguing and hopefully there's more in the future like this.

[nask]

It has to be said, Riley is a great presenter. He's got such great comedic timing hahaha

[dennislacroix]

Was never really someone into mechanical type devices but this, this is a beautiful work of art if you ask me. You won't get the those sounds of work being done with digital equipment. Who remembers the sound of grunting floppy drives when you turned on the computer? Now everything is just silent.

[jimmypockrus]

I worked for a structural steel detailer back in 1983. Structural steel details for architectural drawings is done in feet, inches and fractions of inches, 1/2, 1/4, 1/8, 1/16, 1/32, & 1/64 of an inch. We had a calculator similar to this one but was about 2 1/2 times wider than this on and had over 100 keys. It was amazing to watch it add, subtract, multiply and divide with fractions to out to 63/64" It would spin and click for about a minute and spit out an answer. How it was able to find a common denominator for an entire list of fractions, convert all the fractions to the same denominator. perform the math function and split out the corrict answer. We did all of the math long hand on paper and used the desktop sized computer to check our math. Over 42 years of working in things have really changed with the computers that I have used but there are still things like calculating parts of a circle or curve that I have to rely on pencil and paper because the programmers of the drafting software don't always give us all the tools we need.

[xTJ]

I absolutely love these mechanical calculators. It's still wild to me that they could design these.

[fyzxnerd]

I cannot help but notice the fact that Riley is wearing A very, surprisingly, similar outfit to Technology Connections.

[mikkelgeorgsen]

Amazing cinematography and Riley's comedic timing is on point - one of the best LTT videos yet!

[richfiles]

Interestingly enough, Friden also made the SRW-10, which had a single key square root calculation function! It basically automated the process demonstrated in this video. They are something of a holy grail to vintage calculating machine collectors. I wish I had one! I do have a pair of STW-10s, like the one featured in this video, that I'd love to restore someday. I have a massive collection of both mechanical and electronic adding machines and calculators. One of my STW-10s is fully jammed, but the other only has a frozen multiplicand advance. The accumulator will happily sit there and multiply any number for eternity. It only got "stuck" in the past decade or so, so I think it may be mostly a lubrication issue... I hope. I'm just not set up with the needed space to even consider attempting repairs right now... As for my collection, I have a Sony Sobax ICC-600W that I fully restored (the nixie tube calculator famous from the Superposition benchmark), as well as an SCM Cogito 240SR, a Friden EC-132 (square root version of the EC-130 featured in this video), an HP 9100A (Hewlett Packard's first calculator), an HP 9825 (a "calculator" that ran a 16-bit CPU at 10 MHz, with up to 32K RAM, in 1976... It was a calculator in name only, and literally a ploy to let engineers get a computer on their desk at a time when there was often a lot of red tape for a business to approve a computer, but not a calculator, LOL), and many, many other machines! I have over 100 pocket and desktop machines!

[Neojhun]

When LMG brings out the Tweed Jacket. It's going to be a powerhouse of a shortfilm.

[rajikkali]

The evolution of this channel is incredible