An intriguing post on twitter today caught my eye. John Brooks, creator of ProDOS 2.4.1 has released a short program which scrolls Apple II gs text at 130 frames per second at 2.8 MHz.
John is known not only for his recently released updates to the ProDOS operating system but also for his Bitsy Bye file manager on the Apple II series and the A.P.P.L.E. produced TurtleSoft ProDOS version as well as his old days fame for The Apple II gs game Rastan,
John has recently re-entered the Apple II programming community and since reappearing has been extremely prolific on a bevy of projects across the spectrum.
And now without further delay is the code for the $52 Byte John Brooks text scroller:
For those of you who need the actual text of the program, we have entered the program for you here:
———John Brooks Text Scroller Program Listing———–
0300:18 FB C2 20 0B A2 08 A0 01 E0 30 B9 53 C0 BD F8
0310:03 5B BD 78 04 9D F8 03 BD F8 04 9D 78 04 BD 78
0320:05 9D F8 04 BD F8 05 9D 78 05 BD 78 06 9D F8 05
0330:BD F8 06 9D 78 06 BD 78 07 9D F8 06 90 0A 7B 9D
0340:50 07 A9 A0 A0 9D 78 07 88 10 C0 E8 E8 10 B8 2B
——End of Listing———-
Once you have entered the program, it can be saved by typing:
BSAVE SCROLLER, A$300, L$52
To activate the program and utilize it, the 80 Column mode of the Apple II gs will need to be active. You can execute the program by performing a CALL 768 and the program will scroll the screen up one line while clearing the last line on the screen.
For those of you who like the actual Assembly language listings, John has been kind enough to provide A.P.P.L.E. with the screen shots of those as well: