Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!mcgill-vision!bloom-beacon!eru!luth!sunic!mcsun!ukc!dcl-cs!gdt!mapjilg
From: mapjilg@bath.ac.uk (J I L Gold)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Amiga Sprites - why do they do this?
Message-ID: <1990Feb6.103646.11621@bath.ac.uk>
Date: 6 Feb 90 10:36:46 GMT
References: <16943@eerie.acsu.Buffalo.EDU>
Organization: Bath University Computing Services, UK
Lines: 28

In article <16943@eerie.acsu.Buffalo.EDU> gbbrooks@sybil.cs.buffalo.edu (G. Brandon Brooks) writes:
>
>	I ran across this strange occurance about a month ago, and I was
>wondering if anyone here could explain the cause of this.

>	Okay, what apparently happens is that if the SAME TWO numbers appear
>on the same line, the first of the doubled digit will not appear.
>	I took the pictures from the SAME memory location, in that:
>	Sprite[1].posctldata := (example) 1234567;
>        Sprite[2].posctldata := 1234567;
>
>	But, if I copy the data in 1234567 to another location, say 11111,
>        Sprite[1].posctldata := 1234567;
>        Sprite[1].posctldata := 11111;
>	The NUMBERS DO NOT DISAPPEAR!!!!!!! 1:55 will appear as 1:55.
>	
>	Why when the data for TWO sprites come from the SAME memory location
>will the Amiga only show ONE of them?????
>

I think this is because you need SEPARATE areas of chip RAM even for identical
sprites in order for the hardware not to lose track of the DMA channels it
needs.


-- 
#  J.Gold                            |    mapjilg@uk.ac.bath.gdr               #
#  University of Bath , UK           |    jilg@uk.ac.bath.maths                #