Marchant Silent Speed model 8M Review / HowTo 

I remember helping dad at the auto parts store with that in the early 70s when we did inventory with this. I was a pre-teen with nothing better to do. I use to love the division because of the musical sound it seemed to make.

My guess is that the reverse setting key has accountants/bookkeepers in mind. Some accounts are shown as a debit balance, and some as a credit for convenience, basically reverses of each other. One way to think of it is your debts are negative money, but we usually show your credit card balance as a positive amount you owe vs a negative amount you have. If you're doing something where you need to add values up from different accounts that show both sign conventions, setting the machine to reverse while you total values could be extremely handy. That way you can keep the muscle memory of hitting the addition key as you accumulate the total.

I generally don't collect electric machines, but I would make an exception for the Marchant Silent Speed or Figuremaster. It has a brilliant mechanism where the register wheels rotate smoothly from start to finish - there is no starting and stopping to handle carries. The register works like an odometer, each digit moving at one tenth the speed of the one to its right, and then at the end of the calculation the wheels are adjusted for display so the digits are in the middle of the windows. Each number wheel of the register has a differential gear system driving it, which adds together the input from the keyboard and this continuous carry from the next lower number wheel. Also, it adds 9 in the same time as it takes to add 1, because each column of keys is basically a 9-speed gearbox/transmission, feeding into those differentials I mentioned. There is a manual for this machine on my site. From a quick look, the Reverse button is mostly used to subtract products. www.jaapsch.net/mechcalc/marchant.htm#manuals

I have just finished restoring one of these back to working condition, it has been a challenge but got there in the end 🙂 It is an amazing machine, much more refined than my others, even without the case on it is almost silent (compared to my Diehl which would wake half the street).

I love how excited the intro music is

I used a Marchant to inventory grocery stores in 1971. Fed numbers as fast as it would take them for hours. Loved the sound.

Adding backwards? I know an example. I worked in a company where they count seperate articles, often hundreds of them. You can easily lose count so they do that with a scanner (the same ID must be scanned x times). In some occasions they get random numbers of articles, so they count a second time but backwards to verify the result.

The Friden EC-130 electronic desk calculator came out in 1963, and in 1965 it was joined by the EC-132, which could take square roots. They cost over $2000, though, so they didn’t immediately take over the market.

Oh no wonder I found this channel in my recommended recently - I've been binge watching your adding machines, and once I got to this one, I got some serious deja vu Turns out, I watched a division by 0 on a very similar machine back in 2016 RU-vid's good at that, assuming I'll still like what I liked 6 years ago

I would imagine the Reverse key is just an 'undo' button. Not so great given that it loses the keyboard contents, but if you are paying attention to the input display and see you have entered incorrectly, then Reverse plus whatever you incorrectly keyed plus whatever operation you did should restore the running total. I do remember the divide by zero problem on this type of calculator. In the undergraduate physics lab in 1971 we used a calculator working on the same principles (sorry, don't know what brand, this was in the UK, and I imagine the machine dated from the mid-60's). The second-year students supervising would stand behind the prettiest girl using the machine, key in a divide by zero over her shoulder, then laugh at her panic as the carriage went mad - the theory being that she'd be so grateful for being rescued, the saviour would get a date - I doubt if it worked. This was about 18 months before HP solved the entire problem at a stroke. My father was a design engineer and his design office had a variety of such machines for stress calcs, including a Curta which he brought home to show me in about 1967 or so, plus all the slide rules you could wish for. The instant the HP machines came out they bought 10 and that was the end of all that, though I still have his 20" slide rule on which he was very quick.

The margent “silent” speed 8M adding machine being “ silent” ahahaha it’s everything except being silent,but apart from that it’s still an amezing machine.

Always wanted one.

Reverse probably helps with negative numbers. If you wanted to add to a negative number it would be easier to keep track what you are doing if you don't have to change the operator. -5 + 2 usually you would have to turn it into 5 - 2 for a machine that doesn't allow negative inputs. Using reverse as the negative part you can input the number and operator as you see them, in this case 'reverse' > '5' > '+' > '2' and then flip the sign on the result.

Ha, Charles Babbage would be proud!

Reverse is for when you have to subtract a product from your working total. Do one negative multiplication and get it directly, rather than having to write down and re-key your intermediate values.

Estas calculadoras foram utilizadas no projeto Manhatan

what happens when you auto-divide by zero?

My Curta has the same addition-subtraction swap button. I believe it's for division by subtraction.

Superbe :-)

What the fuck, that is an honestly amazing machine!

How did it compare to the Friden STW 10 in speed?

surprised you didn't try auto dividing by 0 to see what would happen

So how do you know where to put the decimal when dividing?

from when it started doing multiplication my jaw hung open and I sat in shock until a couple of minutes after the video at the shear mechanical complexity of it The transistor was a mistake

luckily this wonderfull machine is not as silent as its name sugests... i love the sound

It'a Calculator, not an Adding Machine. Adding Machines were never intended to multiply until Odhner released their model XX which had short cut multiplication

My Dad pronounced it Mar-shawn

-BASEMENT- FILM STUDIO 😂

great video if you ever want to sell it for $12 bucks let me know!

hello again, mister staecker. i have tried to contact you via your website, announced in the chanal-informations, but it didn't work out. is this website permanently of-line or is it maybe that i have acces-problems to it from germany? i wanted to contact you about the use of some sound-recordings of the silent speed in your video for music. best regards, chris