Kyle Rankin @kyle@librem.one

@Konqi It underscores how much of what seems intuitive comes down to what you have already experienced. I bet in 30 years current calculator interfaces will seem hard and confusing, as people will be used to asking voice assistants instead.

@Konqi It has the advantage of an electric motor to take the place of levers and cranks. It also seems easier because the UI is closer to modern calculators we are more familiar with, which makes sense, since electronic calculators started coming out a bit over a decade later.

While they aren't as pretty as Burroughs adding machines, Comptometers are *fast* and functional (you can calculate square roots on them!) and are my favorite from this era. There's a reason they stuck around with only minor tweaks until the age of electronic calculators.

This red button is part of the control key mechanism. Operators touch-typed, and partial key presses would increment the register only partway. If you press a key part-way down, all other columns lock until you go back and fix that column and press the red button to clear.

To clear the register, pull the lever back then forward. It makes a satisfying noise when the register clears or carries. This was designed for mostly one-handed operation and future revisions just require you to pull the lever forward to clear.

You do division w/ repeated subtraction using small digits (minus one!) starting from the left, shifting right when leftmost digit in dividend is 0. You don't use the front switch so that carried digits form the quotient in the register. Here is 145 / 12 = 12 remainder 1.

Multiplication is easy and fast. Just do repeated addition for the first digit in the multiplier and shift left until each digit is accounted for. Here is 768 x 1024.

To subtract, use the small digits on the keys instead of the large, subtract one from the subtrahend, and hold down the correct switch in the front to prevent the one from carrying. To do 31342 - 42, I press 41 in small digits (58 in large digits) while holding the front switch.

Like with other Comptometers, you just press corresponding keys to add. Trained Comptometer operators performed calculations by feel (odd keys were concave, even were flat) and mostly one-handed so their eyes and left hand could stay on the sheet of figures. Here's 31337 + 5.

The Comptometer to the right is a Model F, made between 1919 and 1920. It is the mass-produced successor to the smaller (and rarer) Model E (1913-1914) to the left. The Model E introduced a "control-key" mechanism to prevent errors from half-presses, but Model F simplified it.

@elb It's a National Cash Register Model 11-EN made in the early 1950s. NCR was better known for their ornate cash registers, but they also made electromechanical adding machines like this one. They apparently were also involved in manufacturing electromechanical Bombe computers during WWII to crack Enigma.

I'm not add-icted. I can subtract whenever I want. Of course to subtract I would need to add something complementary...

The server's anti-virus wasn't up to date... https://arstechnica.com/information-technology/2021/10/passengers-couldnt-fly-after-nhs-vaccine-passport-went-offline/

@jlcrawf There's more to come! I'm going to feature a new one weekly, spaced out so as not to deluge my timeline all at once.

@ajmartinez There is also this, but the original site is offline now so we'd have to rely on wayback machine: https://www.thingiverse.com/thing:1813308

@ajmartinez That would be an incredibly fun project. Most of the replica kits I see out there just replicate the outside, the inside is an arduino or similar. I'd love to replicate a mechanical version.

Apparently there are CAD renders here: https://grabcad.com/library/enigma-machine-replica-1#!

Eventually John Conner will drop from the future into that street. That much is known, the machines just don't know exactly when. https://sanfrancisco.cbslocal.com/2021/10/14/dead-end-sf-street-plagued-with-confused-waymo-cars-trying-to-turn-around-every-5-minutes/

We are testing out a new experimental feature in PureBoot to extend tamper detection past /boot into the root disk. I write about the feature and my thought process behind developing it here: https://puri.sm/posts/new-pureboot-feature-scanning-root-for-tampering/

"I'm really into mechanical calculators and also security. A mechanical cipher machine would be really cool to add to the collection." Then I saw the going rates for vintage WWII cipher machines... #nope #toorichformyblood