A 8 bits register that can do multiple operations
A demonstration of how to make it work with bigger values is included
D Flip Flop made from NOT and OR gates
Just for fun. 8 Bit register and 4 of those registers combined to make a shift register.
This was the final project for the college course Logic Design. The idea for the project was taken from CSE/EEE 120 Capstone Design Project Spring 2021, ASU, Tempe, Arizona, Prof. of Practice, Steven Millman (NXP).
Hello,
I have built a fully working converter that converts 16-bit binary code to BCD.
I wanted a mode with a small amount of gates instead of millions of cells connected in series to ROM. As a result, I designed the converter in a slightly different way, using only 5 ROM cells, one register, one shift register and, of course, since this is an algorithm where the operation is performed by cyclically changing one piece of data, we also need a control unit. This is only for clock control and a few minor details.
This conversion method is generally referred to as double-dabble, also known as shift-and-add-3. In fact, it is a large number of ROM cells, each cell handling a 4-bit or BCD code. It works by adding 3 to all numbers greater than or equal to 5, then shifting the entire range of bits to the left once. This cycle is repeated as many times as the length of the input bits, for example we have 8 bits and the cycle will be repeated eight times.
The main difference between my converter and the others is that mine is done by a clock that is constantly blinking, and drives the cyclical circulation of a piece of data continuously across exactly the same pair of cells. This method reduces the number of gates, but may be slightly slower and more complicated. While other circuits are mostly built with series connected ROM cells and this results in a simple circuit but a higher gate count compared to mine.
Below I have attached an image of one ROM cell that converts binary code to BCD. There is also a table that describes the behaviour of this cell perfectly.
I hope you like the plan. I hope you enjoy the experience.