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From: pochron@cat53.cs.wisc.edu (David Pochron)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: The Copper / HW level programming.
Summary: The Copper and time it takes
Keywords: Copper Move
Message-ID: <1991Feb19.194313.29117@daffy.cs.wisc.edu>
Date: 19 Feb 91 19:43:13 GMT
References: <1991Feb11.162007.7750@vax1.tcd.ie>
Sender: news@daffy.cs.wisc.edu (The News)
Organization: U of Wisconsin CS Dept
Lines: 34

In article <1991Feb11.162007.7750@vax1.tcd.ie> smcgerty@vax1.tcd.ie writes:
>Does anyone know how long a Copper MOVE instruction takes?
>I'm curious to know how many CMOVEs I can do in one scan line...

Well, I vaguely recall that you only have time to change 16 color registers
in one scan line...

>Assuming the CWAIT finishes when the raster hits the point it specifies, will a
>CMOVE straight after it effect that position/pixel, or will it be too late? 

Good question.  I have played around witht hardware out of curiosity and
found the WAIT instruction to be extremely accurate as to when the next
instruction would take effect - like programming a Copper list to change the
screen color 2/3s the way across the screen.  The change is perfectly vertical
so either the MOVE instr. fetch/execute time is right on the mark each time,
or the Copper pre-loads the next instruction after a WAIT so it can make the
change at the exact pixel. (More likely)

The closest I have been able to get a color change to occur on a single
scanline has been 16 pixels apart, by just doing two MOVE's one after the
other.  I guess you could say it take 1 bitplane DMA word for an instruction
to execute, but this is just guessing on my part.

>----------------------------------------------------------------------------
>|  / T | /  Stephen John McGerty           |                     Amiga  // |
>|  / | |/   smcgerty@vax1.tcd.ie (C.Sci.)  | "Hmm.. No, nothing."    \\//  |
>|__________________________________________|_______________________________|


-- 

       -- David M. Pochron   | "Life's a blit,
                             |  and then you VBI."
pochron@garfield.cs.wisc.edu |