And they then wrote code,  usually machine code, sometimes binary code, which was then sent by mail to a data center to be punched onto paper tape or card and then re-punched,  in order to verify it.
Escrivien codi, normalment codi de màquina a vegades codi binari que després s'enviava per correu a un centre de dades per a ser perforat en una cinta de paper o targeta i després es tornaven a perforar per verificar-se.