Category : Files from Magazines
Archive   : VOL7N20.ZIP
Filename : BIGGER.PAS

PROGRAM Bigger_Screen;
CONST
Wide = 150; { You can ajust the size of the virtual screen }
Long = 40; { by changing these two constants }
Nline = 25; { change to 24 if your monitor display only 24 lines }

TYPE
Scr = ARRAY[1..Nline, 1..80, 1..2] OF Char;
LongString = STRING[255];

VAR
MonoD : Scr ABSOLUTE $B000 : 0000;
ColoD : Scr ABSOLUTE $B800 : 0000;
Mode : Byte ABSOLUTE $0040 : $0049; { video mode }
BigScr : ARRAY[1..Long, 1..Wide, 1..2] OF Char;

PROCEDURE Big_ClrScr;
VAR I : Integer;
BEGIN
FOR I := 1 TO Wide DO
BEGIN
BigScr[1, i, 1] := Chr(32);
BigScr[1, i, 2] := Chr(15);
END;
FOR I := 2 TO Long DO Move(BigScr[1, 1, 1], BigScr[i, 1, 1], Wide*2)
END;

PROCEDURE Big_Write(Line : LongString; Col, Row : Integer; VidAtt : Byte);
VAR I : Integer;
BEGIN
IF (Row <= Long) THEN
FOR I := 0 TO Length(Line)-1 DO
IF (Col+i) <= Wide THEN
BEGIN
BigScr[Row, Col+i, 1] := Line[i+1];
BigScr[Row, Col+i, 2] := Chr(VidAtt);
END;
END;

PROCEDURE Show_BigScr(col, Row : Integer);
VAR I : Integer;
BEGIN
FOR I := 1 TO Nline DO
CASE Mode OF
7 : Move(BigScr[i+col-1, row, 1], MonoD[I, 1, 1], 160);
2, 3 : Move(BigScr[i+col-1, row, 1], ColoD[I, 1, 1], 160);
END;
END;

PROCEDURE GetMove;
VAR
Ch1, Ch2 : Char;
PosX, PosY : Integer;
BEGIN
PosX := 1; PosY := 1;
ClrScr;
REPEAT
Show_BigScr(PosX, PosY);
Read(Kbd, Ch1);
IF Ch1 = Chr(27) THEN
BEGIN
Read(Kbd, Ch2);
CASE Ord(Ch2) OF
72 : IF PosX > 1 THEN PosX := Pred(PosX); {up }
77 : IF PosY < Wide-79 THEN PosY := Succ(PosY); {right}
80 : IF PosX < Long-Pred(Nline) THEN
PosX := Succ(PosX); {down }
75 : IF PosY > 1 THEN PosY := Pred(PosY); {left }
END;
END;
UNTIL Ch1 = Chr(13);
END;

BEGIN
Big_ClrScr;
Big_Write('<- this is the upper left corner of the screen',
1, 1, White);
Big_Write('Use arrow keys to move the "viewport"; press to quit',
1, 2, White);
Big_Write('<- this is the middle of the screen',
Wide DIV 2, Long DIV 2, Red);
Big_Write('this is the lower right corner of the screen ->',
Wide-46, Long, 25);
GetMove;
END.