Monroe Ii 620 NIXIE tube calculator!!

[HNickProg]

the knob with 1 to 6 probably sets the decimal point and the switch underneath it is for choosing in which direction it rounds like round up from 5 or round to even number

[wanghaoyu6]

You lucky bastard!!

[bairdy102]

I think the dial controls the number of decimal places

[TheGreatRunaway]

I LOVE NIXIE TUBES :DDDDDDDDDDDDDD



[hifijohn]

i love those nixie tube displays. each digital was a seperate anode in a shape of the digit and was in a different plane.so as the numbers changed they would move towards you and back from you.

[faffaflunkie]

Wow. There must have been a ton of dust on that thing.

[Audinos]

I bought one of these for $10 at a junk store. These were made around 1972. Mine has 16 digits, plus commas to separate thousands lit by neon bulbs. Mine also has neon lights with small, clear, beehive-shaped lenses over the keys for Memory 1, Memory 2, multiply, and divide, which light up when those keys are pressed. The "LI" on the front stands for Litton, which I believed purchased the Monroe company around that time.

[ubercoolman7]

this is awesome. how did you get it for?

[CassetteMaster]

@ubercoolman7 I think 8 dollars.

[ubercoolman7]

@CassetteMaster lucky. i would have been very happy to get one of those for $8. they're really expensive on ebay

[OttomanDrifter91]

from now on i wil use my calculator as the way you do: 'e-e-e-e-e-e-e-e-e-eight' :D

[ELTIGREROCKS10NEW]

The dial sets the amount of decimals that go in even if the decimal is 0. That is why it said 654324.0000 set it to 0 & it will be normal.

[baneskrbic]

Try dividing by 0.

[richfiles]

The "K" key sets it into constant mode. Say you do 2x2. If it's not in constant mode, you have to type x and 2 every single time. If you press the "K" key, and then enter 2x2, then every time you hit the "+ =" key it automatically recalls that you are multiplying by 2 and will do the correct multiplication every time you hit the "+ =" key. 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, and so on. With "K" up, it won't do that.

[richfiles]

The dial is your decimal selector. It sets the number of decimal places to the right of the decimal. The "4/5" switch is the rounding switch. An example, turn the dial to 2, and the switch to "4/5", and type 5+15, and you should get "00000000020.00" then try 20 divide by 3. The answer is "6.666666666666" on a modern calculator, but since the dial is set to 2, it will show "00000000006.67". Flip the "4/5" switch to the down arrow. Do 20 divided by 3 and it rounds down to "00000000006.66".

[richfiles]

My oldest electronic desktop calculator is either a Monroe 925 or an Elektronika 4-71b (Made in USSR). I think the Monroe is older. I have a Canon 163 on the way, being delivered by post. My oldest pocket calculator is a Canon Pocketronic. I have repaired a couple old models, including two Commodore N-60 navigators and a Commodore S-61 Statistician. That's an awesome find! Those Nixie tubes just can't be beat by any modern segment or pixel display. They are beautifully retro!

[chronius9]

@richfiles Monroe is older, Elektronika model is pretty late - start of 80s. Se 4-71b has primitive Led display, while monroe still uses nixie tubes. In Soviet union nixie tubes was only used in military and science aplications, not to be mass produced.

[heatherandpaul2]

HOLY SHIT!!!! LOVE IT!

[utubefreak6]

how do i replace nixie tubes safely i'm 12?

plzzz answer

[tbsla13]

Does it hum and make lots of heat? I love the cyber-punk aura of nixie tubes!

[polonium9]

we, in the science world, call this an EPIC FIND!!!!!

[laurdy]

put in anything divided by zero and see what it does

[onionofdeath]

and nowadays we have the ti calcs that can perform calculus and still fit in a pocket

[turierik1996]

lol nixies :D

[rottenapples3]

and how did you get it for so cheap.

[CassetteMaster]

It was there at an estate sale.

[ignatei]

@CassetteMaster I see the calculator is plugged to the mains! These tubes require a lot of voltage. But are there any nixie tubes which run on low voltages? I've seen nixie tubes used in a watch operating with a 3 v battery, how is that possible?

[CassetteMaster]

@ignatei Assuming they all need a high voltage, the 3V watch probably has a high voltage generator inside.

[rottenapples3]

Where Did you Get That!!!

[CoolDudeClem]

I'd like to have one of those, and have a clock that uses these.

[Audinos]

I have one of these also. Mine was made in 1972, which is probably about the same age as yours.

[ibcnunabit]

The dial is for how many digits behind the decimal to truncate or round. The 5/4 switch, if disabled, means that it just truncates. If enabled, it rounds up if the next decimal is 5 or greater, and rounds down if it is 4 or less.

[TeamNES1]

In mathematical terms, "Fixed notation."

[ibcnunabit]

Great find!  Love it.

[scottyfixit]

That's Cool!!!

[douro20]

It's an all-LSI machine made by Canon.

[douro20]

That's the Monroe Calculator Division of Litton Industries.

[PineBrookMotorLodge]

Be careful when handling the overflow light, if its neon, I don't know how much electricity the ligt takes, all I know is that the Pine Brook Motor Lodge sign is powered by 5100 volts.

[gomemdesoto]

The HV in this calculator would normally be around 180VDC for running the neon nixie tubes. Neon signs of course been rather bigger, need a much higher voltage.

[douro20]

I used to have a much older machine than this (it had a delay line in it!) which had a 240V supply for the display circuit.

[PineBrookMotorLodge]

RV may stand for Repeat, and the V for ?

On my featured video, my electro-mechanical adding machine by Monroe has a button labeled R for repeat.

[PineBrookMotorLodge]

By the way, mine is from 1935.

[t0nito]

The dial is for the number of decimal points for instance if you have the dial on 4 1+1=2.000 if you have it on 2 1+1=2.00 on zero 1+1=2

[thegenrl]

you need some video skills, show the fucking calculator and stop moving the camera all over like a moron.

[tommybshr]

groundskeeper from caddyshack?

[bejius]

Luky bastard, 8 usd, that's too cheap ;-), I also wonder what kind of chip runs this baby.

[gomemdesoto]

4 Texas Instruments chips run this calculator. TMC01807, TMC1733A, TMC1753, TMC1754 ... if that's any help? :)

[VideyoJunkei]

the dial sets the decimal point position, like use '2' for adding dollars and cents...

[plateshutoverlock]

does the star and diamond mean Multiply and Divide respectively?

[Crosxerx]

The dial might also set the brightness of the Nixies

[themaritimeman]

I love Vintage calculators! Especially ones with Vacuum-Fluorescent displays and Nixie tubes! Thanks for posting this!

[videogameknowitall]

Sweet! :-)

[coolbluelights]

Nixie tubes? wow never heard of those before, that's wicked cool !!

[FEXAMON3]

thanks! now I now use my monroe 620!

[Membrane556]

Did a search on Google seems it's logic is divided between 4 LSI chips designed for the task surprisingly advanced for a piece from 1972.

[Membrane556]

Cool old find I wonder if it runs an intel 4004 or TI TMS1000 4bit microprocessor since the logic PCB appears to be a single board under the keyboard.

[raymondleeleggs]

Awesome!

[zzz11y]

omg, my laptop is smaller than it

[tubeie07]

Love those Nixie tubes! Reminds me of some old movie where a 60's mainframe computer is trying to work out a calculation to get men back from outer space or such! Cool look!

[WillWatchAnything]

I belive the number dail sets the number of decimal places. Setting it to zero should round up to the next whole number.

[rockangel1967]

yep. just had the same in mind

[Trance88]

Nice! Very early set. Looks like it's from the early 70's.

[retrochad]

The "LI" stands for Litton Industries...a conglomerate which also manufactured microwave ovens, Westrex film sound systems, etc.

I really like the nixies too! The dial I think is to set the number of decimal places.

[wilkes85]

wow ive never seen such a modern looking calculator that used them types of tubes for the display! U gonna use this thing when got homework to do?

[AllAmericanFiveRadio]

Nixie for ever!