A New Case for the KIM Uno

My first KIM Uno project was to make a new case for it. Because I am not that much into modern technology, I decided to build it the old-fashioned way, using sheets of plastic, cutters, glue, and screws — technology from the time of the original KIM-1.

Bill of materials:

The microswitches on the PCB are quite nice, so I wanted to keep them and just add bigger caps.

The front plate for the caps is just a sheet of polystyrene with holes drilled into it, and the caps are made from a leftover piece of sprue runner (a rod made of polystyrene). The plate is 2mm thick and made from black PS.

The caps are glued to small 1mm sheets of PS so that they do not fall out of the front plate later. The markings on the plate are carved free-hand with a milling drill and then painted. Excess paint will be sanded off later.

The proper distance between the front plate and the PCB is paramount when fitting the keypad. There are small spacers made from PS sheet next to the screws.

The body of the case is a simple box of 3mm PS sheets that is open on two sides, the "front" where the keypad and the display are located, and the "top". There are rails made from PS sheets on the inside, so the KIM Uno slides into the body and sits firmly.

The lid is made from 3mm PS and 3mm red acrylic glass sheets. The acrylic glass is still under its protective film at this point. There is a notch on the right side where the power switch will be inserted.

The lid will be held in place by a pair of M3 screws. I made two nuts with steel on the inside and PS on the outside, so they can be glued to the case. I am sure that you can buy such things somewhere, but I did not bother to search.

There is not much room in the battery compartment. I even had to cut off the plastic sheet around the battery contacts. The power switch on the PCB will later be left in the "on" position, because the real power switch will be in the lid.

On the finished lid most of the acrylic glass is covered by 2mm PS. Protective film is still attached to the backside of the glass. The power switch is fixed with two 2mm wood screws.

The finished calculator has the size of a regular pocket calculator, although it is quite a bit thicker than a modern calculator. It still fits comfortably in the palm of a hand.

Next step: write some pocket calculator program for it. (Yes, I know that the KIM Uno has one in its ROM — I am not happy with it.)

Update: after getting the serial connection over FTDI to work, I added a connector for the FDTI adapter to the case. The connector is made from PS sheets and lots of glue to keep the pins in place. It is glued to the bottom of the case.

FTDI adapter connector to the KIM Uno. Everything works fine now.

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