Как работают?

program zbil6_5; 
const p=' ';
var s:real;  i,j,n:integer;
    begin  writeln(' vopr. 5');
    s:=0; i:=0;while i<5 do i:=i+1; s:=s/i;
     writeln('s=',s,'i=',i);
     for i:=1 to 3 do
      for j:=1 to i do begin n:=(10*j+i) div j;
  writeln(i,p,j,p,n);end;end.

program test6;
Type computer=(processor,mouse,printer,monitor);
 var a,b:computer; t:(new,old); f:text;
 Begin assign(f,'test6r.pas');rewrite(f);
 {1} a:=monitor;  {2}b:=printer;{3} writeln(f,'3 ',a=b);
{4}t:=old; {5} Writeln(f,'5',t);
{6} b:=new;
{7}if a<=printer then writeln(f,'7-tak') else writeln(f,'7-ni');
{8}if b<processor then writeln(f,'8-tak') else writeln(f,'8-ni');
{9}if t<new then writeln(f,'9-tak') else writeln(f,'9-ni');
{10}if succ(mouse)=monitor then writeln(f,'10-tak') else writeln(10,'7-ni');
{11}t:=pred(t);
{12} writeln(f,'12-mouse-',t) ;
{13}writeln(f,'13 ','s=',ord(processor)+ord(old)); write(f,'14 ');
{14}for a:=mouse to printer  do write(f,'6*'); close(f);end.

Program stringkont6;
var str:string[8];    str1:string[9];    str2:string[6];    str3:string[5];    l,i,j:integer;
    begin str1:='rabbit'; str3:=str1;
    Writeln(str1,'  ',str3);
    str2:='radar';   Writeln(str2);    i:=pos('r',str2);  writeln('i=',i);
    delete(str2,i,2); ;writeln(str2);    l:=pos('b',str1);  writeln('l=',l);
     delete(str1,l,4);    Writeln(str1);    insert('dio',str1,l); writeln(str1);
    j:=ord(str1[0]);Writeln(j);        end.

var set1,set2,set3,set4,set5:charset;    i:char;
    begin set1:=['d','g','o','j','l'];    set2:=['c','a','t'];    set3:=set2-['x','a'];
    set4:=[];    set5:=['w','r','i','t','h'];
    {1}if 'z' in set1 then  Write('  ','true') else   Write('  ','false');
    {2}if set1=set2 then  Write('  ','true') else   Write('  ','false');
    {3}if not(set3=set5) then  Write('  ','true') else   Write('  ','false');
    writeln;     writeln('       set3       ');    writeln;
    for i:='a' to 'z' do    if i in set3 then  Write('  ',i);
    set1:=set1+['m','o','u','s','e'] ;    set2:=set2+['m','u'];    set4:=set2*set1;
    writeln;     write('       set1       ');     writeln;
    for i:='a' to 'z' do    if i in set1 then  Write('  ',i);   end.