Wie sieht ein Beispielprogramm mit graph.tpu für Turbo Pascal 7 unter DOSBox aus?

Here is a simple example program in Turbo Pascal 7 (TP7) using the `graph.tpu` unit. This program initializes the graphics mode, draws a line, waits for a keypress, and then closes the graphics mode. You can run this under DOSBox with TP7.

```pascal
program SimpleGraphDemo;
uses graph, crt;

var
gd, gm: integer;

begin
gd := detect;
initgraph(gd, gm, '');

if graphresult <> grOk then
begin
writeln('Graphics error: ', grapherrormsg(graphresult));
halt(1);
end;

line(100, 100, 300, 300); { Draw a line from (100,100) to (300,300) }

outtextxy(120, 90, 'Press any key to exit...');
readkey;

closegraph;
end.
```

**Instructions:**
1. Save this code as `GRAPHDEMO.PAS`.
2. Compile it in Turbo Pascal 7 under DOSBox.
3. Make sure `graph.tpu` and the BGI driver files (e.g., `EGAVGA.BGI`) are in the same directory or specify the path in `initgraph`.

For more information about Turbo Pascal and its graphics unit, see [Turbo Pascal resources](https://pascal-programming.info/).