Re: [stella] Grid demo

Subject: Re: [stella] Grid demo
From: emooney@xxxxxxxxxxxxxxxx (Erik Mooney)
Date: Thu, 29 Oct 1998 22:50:52 GMT
>> When you say "the prior line only had one RESPx", where exactly is the
>> position of that RESP0?  If that RESP0 is at position, say, 40... then on
>> the next line you hit RESP0 again at 40, you will get a sprite at position
>> 40, but it was caused by the *first* line's RESP0, not the second.  Because
>> 40 is the current position of the sprite, it starts displaying at position
>> 40, because the RESP0 for line 2 hasn't happened yet - as far as the TIA is
>> concerned, it's simply a standard sprite positioning and display.
>
>You know, this has always been a very confusing point to me.  The idea
>that you do your RESPx to set up for the next line.  If it's true, it
>means that when you're doing multiple RESPx on a line, then somehow, TIA
>is buffering them, remembering them all for the next line.  I don't know
>about that...  I tend to think about TIA as if it's rendering in real
>time, reacting to RESPx pretty much right away.  But I'm probably
>wrong... ;-)

The idea is *usually* that you do your RESPx to set up for the next line,
yes.  Think of it that any hit to RESP0 takes effect *eight pixels after
the hit*, which I'm almost sure is correct.  It matches all of what you've
said, as well as Eckhard's observations.  The TIA doesn't buffer any
previous-line hits except for the last - it doesn't care how many times you
hit it.  The last one will generate a sprite at that position on the next
line, unless you hit RESP0 again in the meantime.

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