This circuit using only transistors was obtained from Ferranti's 1969 documentation. It can be made from modern transistors. The circuit is 4 bits.
The integrated circuit used in this 90's circuit is not very common today. An equivalent...
This circuit was found in a William Sheets. It has 75 ohms of output impedance and can operate up to 20...
This circuit was obtained directly in the component's datasheet, and in it we have the use of...