Orrall Cornelius completes his game from last issue, this week with the focus on the display list

Lines 10000 to 10202 provide an illustration of display lists. Type these lines in and modify the PRINT statements, and you should see four lines of #6 GRAPHICS 2 at the top of the screen, then 40 lines of GR.8 for your high-resolution drawings (the grid is under the GR.2 writing). Finally, you should get 11 lines of mode 0 for normal text writing.

In line 10133 the program accesses GR.2 by poking location 87 with the graphics mode number, which is 2, and the same in line 10136. The only difference here is that this time it accesses GR.8 by poking location 87 with 8. Accessing GR.0 isn't so simple, as you have to calculate where you want GR.0 to start on the screen (10140-85).

You should try to avoid on-screen input when the display list is still on screen: if the input is too long it may carry on to the bottom of the screen, and this won't look too pleasant. To see this, run the program and break it during the music and display list.

List the program and on the border you'll see black lines stretching from the left of the screen to the right. Once the listing has filled the border the uppermost part of the listing will be pushed up onto the GR.0 listing until it reaches the GR.8 drawing and disappears.