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| From: indi (all posts)
Date: 2001-03-13
Subject: Re: Strange TED 'effect'
|
On Tue, 13 Mar 2001 11:28:59 +0100 (CET), you wrote:
>Hi All,
>
>I have a question that might have not been asked before on
>the list.
>
>There is a well known interesting effect of TED when
>someone POKE-s a zero value (for example) to TED register
>$13 (at address $FF13) : after this the window area starts
>to "wawe" in a funny continuously flowing black&white
>pattern. Its direction is diagonal. TED seems to be doing
>this when we use the characters from ROM area but we write
>an "illegal" value to the $FF13.
>So, does anyone know what could cause this strange effect?
Your pointing the character data down into Zeropage. This changes all the time, and so will the data for the characters. Its just chance it seems to go diagonally, theres probably a few counters down there somehere
If it points at the screen, then you'll get another funny display, but one thats static until you scroll...
Mike
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