Another BASIC demo

Anything Sinclair ZX Basic related; history, development, tips - differences between BASIC on the ZX80 and ZX81
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Shaun_B
Posts: 410
Joined: Wed Apr 22, 2009 10:22 am

Another BASIC demo

Post by Shaun_B » Thu Dec 21, 2017 9:33 pm

I wondered how fast I could update a good chunk of the screen, and then decided to add a scrolly again.

You're welcome :-) Hope you're all having a good one!

Regards,

Shaun.
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Paul
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Joined: Thu May 27, 2010 8:15 am
Location: Germanys west end

Re: Another BASIC demo

Post by Paul » Fri Dec 22, 2017 5:50 am

The fastest version in Basic I know of is using a single print with a string variable containing all the characters of the screen. I used this to show a large walking man on the screen by

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100 PRINT AT A, B;A$
110 PRINT AT A, B;B$
... 
200 GOTO 100
this wasn't tested on a Zeddy so can contain errors. A and B were used because I wasn't sure about value of top left corner.
It's still early...
In theory, there is no difference between theory and practice. But, in practice, there is.

Shaun_B
Posts: 410
Joined: Wed Apr 22, 2009 10:22 am

Re: Another BASIC demo

Post by Shaun_B » Fri Dec 22, 2017 6:00 am

Thanks. I know that using variables is faster on other dialects of BASIC, I just wasn't sure whether this rule applied to the ZX81 as well. I think using my scrolly routine in this thread I could probably get some more speed out of it, and then maybe more animation.

Regards,

Shaun.

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