NRI Model 832 Digital Computer (Winter 2026)
My Model 832 Recreation
Manufactured By: National Radio Institute (NRI)
Release Date: 1971
Designer: Lou Frenzel
The Model 832 shipped as a kit that contained all the parts necessary to build a working digital computer including; 10 PCBs, 75 7400 series ICs with sockets, 140 slide switches, 4 push buttons, 16 lamps, various discrete components, wire, screws, etc. Included was a "Training Kit Manual" which had full schematics and instructions for assembling the Model 832. The end result was housed in a sturdy case with steel sides and a brushed aluminum front panel.
I don't want to discount the power of the Model 832 kit for teaching the digital hardware side that makes this and all computers possible. The Training Kit Manual is very thorough with complete assembly instructions and lots of "experiments" to ensure that you understand what you have just constructed. I would venture to say that a skilled engineer could legitimately reproduce the hardware based on this manual.
My focus however for this projects was on the computing side. I wanted to make a recreation that clearly looks like a Model 832 and more importantly works just like one. In the absence of all that original hardware I used a modern microprocessor to emulate that functionality.
The Computer
Once the Model 832 is assembled you have a fully functional but simple computer with the following characteristics:
8 bit word size
16 bytes of ROM (128 switches)
16 bytes of RAM
3 working registers (Accumulator, B and E)
3 internal registers (Instruction Register, Memory Address, and Program Counter)
7 memory reference instructions
8 additional operate instructions
direct memory addressing
While not much of a computer power wise, I would argue that this simple architecture is perfect for teaching computer concepts. You can easily wrap your head around the whole machine.
Back of the NRI 832 Recreation
My Recreation
So the finished NRI 832 has:
A laser cut and etched front panel
Arduino MEGA 2560 with NRI 832 emulator
140 slide switches
4 push buttons
128 IN4148 signal diodes
16 white 3 mm LEDs
16 470 ohm limiting resistors
lots and lots of wire
The working recreation was donated to the University of Waterloo Computer Museum as a hands on exhibit to preserve their original NRI 832 artifact.
For more details about this project click on the Project Logs link below.
NRI Hardware
You write programs for the Model 832 by entering them directly into ROM memory, yes by setting the positions of the 128 slider switches into the 1 or 0 (up or down) positions. I think this is brilliant (I have a thing for tactile interfaces). No keyboard required. To quote from Louis E. Frenzel, "It is amazing what you can program in just 32 words.".
16 lamps provide more than enough information to understand what is going on inside the machine. No monitor required.
All of the "op codes" available to the machine are printed on the front panel. Additional switches and buttons are clearly labeled and understood. Simple. Straightforward.
Project Logs