Electronic 8421 code adder with decimal display - uses five flip=flop stages per decade with converter to provide decimal display connection

摘要

An electronic adder circuit is designed to add numbers coded in 8421 code and includes a decimal display facility. Each adder circuit provides a decode capability with 5 flip-flops in order to have a capacity for the number 17. The decode adder consists of five flip-flops with the last stage not including an inverter stage. Each flip-flop is formed by a pair of cross-coupled transistors together with diodes and resistors. Inverter stages are provided by a pair of transistors together with a resistor. Carry-overs from a lower stage are introduced to the first stage and the second stage provides an input for a general reset.