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Scroll Down
Posted: Fri Jul 14, 2023 3:48 pm
by MrVertigo
Is it possible to make the screen scroll down using basic on the ZX81, or only up? Like for a skiing program using scroll. Does the skier always have to be at the top of the screen for that simple BASIC trick, or is there a way to have the skier at the bottom?
Re: Scroll Down
Posted: Fri Jul 14, 2023 5:36 pm
by Paul
In pure basic only scrolling up is possible in a reasonable time.
So Horace is always on top of the Hill, not at the bottom
Re: Scroll Down
Posted: Fri Jul 14, 2023 6:29 pm
by MrVertigo
Is there an unpure BASIC way to do it, or does it need full machine code?
Re: Scroll Down
Posted: Fri Jul 14, 2023 8:27 pm
by Paul
There are small machine code routines that offer scrolling in any direction and much more.
Search for
"Inline" BASIC Extensions
Re: Scroll Down
Posted: Fri Jul 14, 2023 8:52 pm
by MrVertigo
Brilliant! Thanks.
Re: Scroll Down
Posted: Fri Jul 14, 2023 10:02 pm
by Moggy
Here's an 8-way scroll routine in M/Code, it should be easy enough for you to adapt to your needs.
Re: Scroll Down
Posted: Fri Jul 14, 2023 10:22 pm
by MrVertigo
Thanks very much
