Pascal III: Changing text modes

The Write and Writeln procedures are unable to send the necessary control
sequences to change the text mode to 40 columns black and white; use the
Unitwrite procedure instead. The correct syntax is:

Program Demo;
Var ans :String;

Procedure Control (number:integer);
Var tryit :CHAR;
Begin
tryit := CHR (number);
Unitwrite (1, tryit, 1, , 12);
End;

Begin
Control (16);
Control (0);
Readln (ANS);
End.