In the tape dump at https://history.dcs.ed.ac.uk/archive/languages/pascal/ Stefano B. found a Pascal P3 source and also a P4 source, not equal to what is found sofar for Pascal P4.
The originator is L.ZAFFALON, CUI, GENEVE.

Here an archive (with the original files from the link above in folder ‘original’) with the Pascal P3 and P4 compiler and interpreter sources

(**********************************************
  *                                            *
  *                                            *
  *         PORTABLE PASCAL COMPILER           *
  *         ************************           *
  *                                            *
  *                PASCAL P3                   *
  *                                            *
  *                                            *
  *     AUTHORS:                               *
  *              URS AMMANN                    *
  *              KESAV NORI                    *
  *              CHRISTIAN JACOBI              *
  *                                            *
  *     ADDRESS:                               *
  *                                            *
  *          INSTITUT FUER INFORMATIK          *
  *          EIDG. TECHNISCHE HOCHSCHULE       *
  *          CH-8096 ZUERICH                   *
  *                                            *
  *                                            *
  *     LAST CHANGES COMPLETED IN MAY 76       *
  *                                            *
  *                                            *
  **********************************************)