Kyle Rankin @kyle@librem.one

You can hold down the subtotal button and pull the lever to print the current total without clearing the register, or you can hold down total to clear the register and print the total. This design is nice in that you can do it all one-handed.

This machine does have one fancy feature: a subtraction button! Instead of the complements method, you can just enter the subtrahend, hit the subtract key and pull the lever. Subtraction prints in red ink! Here I perform 31342 - 42 slowly so you can watch the counter.

Back to the Model 75. To add, enter the first number in the keyboard and pull the lever to add it to the register and print on the paper tape. Then enter the second number and pull the lever again.

It wasn't until the 1950s that trends changed and popular office machines started having green and grey hues, like this early 1950s NCR 11-EN. One big exception was the Comptometer, which kept its brown tones until the 50s when it too shifted to the green/grey aesthetic.

The Burroughs Class 3 I showed earlier in the thread is an example of rebranding a machine originally made by the Pike company. But when 90% of a market looks a certain way, competitors (like this Monroe Model G from 1918) mimic the design. So even in 1946 RC Allen followed suit.

At one point Burroughs controlled about 90% of the adding machine market. It accomplished this like companies today: it bought up its competitors and rebranded their products. That meant painting them black, and instead of felt, they just painted the spot under the keys green.

The Burroughs Class 1 was the first adding machine Burroughs sold starting at the end of the 19th century. It was the Cadillac of adding machines and featured a shiny black case, beveled glass on the sides to show off the mechanism, and actual green felt under the keyboard.

This machine looks and functions largely the same as Burroughs adding machines 30-40 years older. Have you noticed how many machines I've featured (like this Burroughs Class 3) have a black case, and a keyboard with white and black keys on a green background? My theory for why:

This is an RC Allen Model 75 adding/listing machine from around 1946. RC Allen was founded in 1932 in Grand Rapids Michigan and was a distributor of Facit calculators from Sweden. The brand still exists today as a manufacturer of precision aircraft instruments.

Ok I think we are ready for tomorrow.

I fixed the timing but this is as clean as I dare to make it right now. It got wet in storage some time in the past and rust worked its way under the black paint and through part of a screw. The rest of the paint is very flaky. I removed as much surface rust as much as I dared.

Round 2. This time with a Gem portable adding machine from 1941 (I have the original box, receipt, and warranty card) that's rusty *and* has two digits out of time with the rest of the register.

Done! One reason I cleaned it is I smelled that "old appliance" smell and wanted to ensure the motor wasn't strained. I ran it with the cover off and saw flashes in the back. The mechanism disconnects the motor when it's not needed, and that makes it arc. I was smelling ozone!

Time to clean and oil (and this time not have to repair) a National Cash Register 11-EN electro-mechanical adding machine from the early 1950s.

While it's hard to beat the aesthetic appeal of the Burroughs Class 1 and 3, they are big, heavy, and slow. If you don't need a paper record you'd be better served by its 1919 competitors the Comptometer Model F or Monroe Model G I featured here earlier.

You multiply by repeated addition in the ones column, then shift left and repeat for each digit in the multiplicand. Normally the keys reset when you pull the lever, but by pressing the repeat key they stay down until you press the Total key. Here is 12 x 12.

This is an adding machine--it only adds. To subtract, you have to use the complements method. For instance, to subtract 42 from 31342, I convert 42 to its complement (99999958) and add it. The carries shift off the left of the register and the difference remains.

To add, enter the first number in the keyboard and then pull the lever to add it to the register and print it on the tape. The enter the second number and pull the lever again. The lever provides the force necessary to print. Here's 31337 + 5.

The Class 3 is a rather different design from the Class 1. Like tech companies today, Burroughs expanded by buying competitors. This machine was originally made by the Pike company in 1909 which Burroughs bought in 1911 and it became a core part of a larger product line.

This is a Burroughs Class 3 adding machine from 1919. Where the Class 1 I featured here earlier has fancy beveled glass and a full carriage on the back to accept ledgers, this later Class 3 has a simple paper spool and was used for general accounting.