1.  Introduction  The development of the langua;le  Pascal  is based on two principal  aims. The first is to make available a language suitable to teach  programming as a systematic  di~cipline  based on certain fundamental  concepts clearly and naturally rellected by the language. The second is  to develop implementations of this language that are both reliable and  efficient on presently available lomputers.  The  desire  for  a  new  language  for  the  purpose  of teaching  programming is due to my dissatl" faction with the presently used major  languages whose features and co lstruCts too often cannot be explained  logically  and  convincingly  at  d  that  too  often  defy  systematic  reasoning. Along with this dissa' isfaction goes my conviction that the  language in which students are t(.1 ught to express their ideas profoundly  influences their habits of though  t  and invention, and that the disorder  governing  these  languages  Ilirectly  imposes  itself  onto  the  programming style of the students.  There  is  of course  plenty  of reason  to  be  cautious  with  the  introduction of yet another prog-amming language, and the objection  against teaching programming ill a language which is not widely used  and accepted has undoubtedly ..,ome justification, at least based on  short-term commercial reasoning. However, the choice of a language  for teaching based on its  widvspread acceptance and availability,  together with the fact that the Ian  ~uage  most widely taught is therefore  going to be the one most widt  Iy  used, forms the safest recipe for  stagnation in a subject of sucl  profound pedagogical influence. I  consider it therefore well worth ,\'hile to make an effort to break this  vicious circle.  Of course a new language sh, IU  III  not be developed just for the sake  of novelty;  existing  language ,;  should  be  used  as  a  basis  for  development wherever they mt:  .~,t  the criteria mentioned and do not  impede a systematic structure. In  I  hat sense Algol 60 was used as a basis  for Pascal, since it meets the dl mands with respect to teaching to a  much higher degree than  any  other standard language.  Thus the  principles of structuring, and in f.tct the form of expressions, are copied  from Algol 60. It was, however, Ilot deemed appropriate to adopt Algol  60 as a subset of Pascal; certail  construction principles, particularly  142 