Boards in 1 GitHub repository, designed in KiCad, that use the SN74LS20N by Texas Instruments (0℃~+70℃ 15ns@5V,15pF 2 2.7V~3.4V 2V 4 4.75V~5.25V 400uA 500mV 74LS Series 800mV 800uA 8mA NAND Gate DIP-14 Logic Gates ROHS). See how each wires it, with its parts, size, README and files; the SN74LS20N’s symbol, footprint and pinout are on its own page.
ForgottenMachines/Entrex
The technologies documented here will include all like-kind systems manufactured by Nixdorf, Redifon, ROCC & Mera, all originally designed by Entrex Inc, Burlington, MA USA.