"Space Age" decimal computer.

[alex_79]

Last week I stumbled across this youtube video showing a recreation of an old (1966) electronic project for a "Space Age Decimal Computer" (which is actually just an adding machine).

I find the technical explanations (in the page linked in the description of the video, as well as in the original 1966 article) very interesting, but the thing that catched my attention the most is the weird "user interface" of this machine that uses a telephone rotary dial to insert the numbers, a clunky rotary switch to select the position and an array of 60 neon lamps to show the result of the operation. The lamps turn on in sequence showing in real time the counters advancing while receiving the pulses from the dial (in the original design, the lamps are actually an integral part of the counters). To perform subtractions, you enter the 9's complement of each digit of the subtrahend, which are marked on the dial. (Note that in the video the author has to correct the result by manually adding a "1" after the subtraction, but that's due to a small mistake in the construction: the original article states that the "carry" from the "100k" position must be fed back to the input of the counter for the "1" position, but that connection is missing in the replica machine. I made the author aware of this in a comment of the video)

You might wonder: why I'm posting this here, since it has nothing to do with the 2600?

Well... I happen to have a couple of rotary dials (I collected a few vintage phones in the past, so I have some spare parts), and I was so fascinated by the decimal computer that I wanted to recreate the experience of using it... without spending any money and without actually building a huge contraption that would have wasted space and collected dust in the house.

So, I put the dial in a small electrical box and wired to a spare joystick cable.
And then I did this:

dc26.zip

The program uses a driving controller in the left port, to mimick the rotary switch that selects the position and the phone dial connected to the right port to enter the digits. The trigger on the driving controller or the RESET switch on the console resets all positions to "0". In the video I perform the operation written on the piece of paper below the TV and at the end you can see the result indicated by the lamps displayed on the screen.

I'm perfectly aware that this must be the silliest program ever made for the VCS, but I had fun for a few hours, so I'm fine with it.  

BTW, anyone has any great gameplay idea that makes use this new "rotary" controller?

[Andrew Davie]

Very fun; well done!  I think it has about the same audience as the SECAM compatibility on my demos/games. Maybe less so I approve wholeheartedly. Thanks for posting.

You could have a simon-like game where you have to remember phone numbers.

[Al_Nafuur]

BTW, anyone has any great gameplay idea that makes use this new "rotary" controller?

maybe with your dc26 kernel. The 2600 gives a Number to reach, but also selects for you the digit sequence (most digits twice or three times) to enter. You always have to add 1-10 to the selected digit.