For the display I wanted something more interesting than a simple binary readout. I decided to go with the retro look and use some IV-9 russian Numitron tubes that can be conveniently driven by 5V with 20mA of current, the perfect amount to use a 4511 7-segment decoder. The only problem in the way of a steampunk output for my computer was converting the base-16 output of my computer into 3 digits of base-10 binary coded decimals.
Binary coded decimals are exactly what they sound like. The BCD system uses binary values 0-9 to express the base-10 digits that we use every day. For instance, the binary number 132 (10000100) would be 0001-0011-0010 expressed in binary coded decimal. To convert binary to BCD you can either design an incredibly complicated logic circuit to preform the operation, use a read-only memory (ROM) to output the correct values or use the method I chose of using an Arduino to do the conversion.
My friend and I created an Arduino sketch that takes an 8-bit input (0-255) and outputs 3 BCD digits. The output goes to a 3-digit Numitron readout board that I spent a good amount of time on.