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Digger
Registered: Mar 2005
Posts: 447 |
$d011 trickery duplicated text lines
Does any one know the $d011 trick to repeat the first char row? I am trying to cancel badlines on the 8th line of each charline (between cycles 54-57) but it doesn't work. The first line gets duplicated but only twice. |
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Testa
Account closed
Registered: Oct 2004
Posts: 197 |
assiduous: yep i see now.... but i'am still confused.
i have an old source: i repeat the first char row
al the way down with only one $d011 write each 8th line.
if i have used this trick to create 25 text swingers
upper scroll style (no linecrunch)
i remember that you also can abort the duplicated char-raw earlier then rc7.. so you can display more then 25 char-raws.. or do i mess up things here...
edit: oh see now.. i checked my source, i do line
doubeling, i display the first char row over and
over again by fetching the same 40 charpointers again.
you can also do the same without fetching the same
charpointers again. this wil give you some more
free cycles: 40 minus the lda $xx sta $d011 writes to
prevent the badline..
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Digger
Registered: Mar 2005
Posts: 447 |
@Fenek: Thanks! I've seen this part before and I was impressed! Was wondering how did you do it :) I suppose the only disadvantage is the fragmented memory you have to use 25 charset banks (only 80 * 8 = $280 bytes each though, right?) Do you use double buffering there at all? |
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
Wizz did this in 1988:
Broken Ass!
Notice the release id nr :) |
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Oswald
Registered: Apr 2002
Posts: 5126 |
Hello :-)
Before I go into trial and error mode I ask: I want to repeat full rows, but I also want badlines, and preferably the least d011 writes possible. it this possible, and how? :)
judging by cruzer's post doable, but he seemingly talks about toucing d011 every line. |
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Digger
Registered: Mar 2005
Posts: 447 |
@Oswald: Badline will cause to refetch the next charline, and you want to have a badline without that I presume? Why? :D |
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JackAsser
Registered: Jun 2002
Posts: 2038 |
Quote: Hello :-)
Before I go into trial and error mode I ask: I want to repeat full rows, but I also want badlines, and preferably the least d011 writes possible. it this possible, and how? :)
judging by cruzer's post doable, but he seemingly talks about toucing d011 every line.
Just trigger a badline before RC<7. If RC==7 on a badline you’ll go to the next row. This is just an FPP. You will not be able to have full 8 lines high rows, only 7. |
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Oswald
Registered: Apr 2002
Posts: 5126 |
Quote: Just trigger a badline before RC<7. If RC==7 on a badline you’ll go to the next row. This is just an FPP. You will not be able to have full 8 lines high rows, only 7.
ah ok guess this is the easy to do, you can repeat a char row after having any nr of its lines displayed.
but I really really need full 8 lines. impossible? : ( |
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Oswald
Registered: Apr 2002
Posts: 5126 |
Quote: @Oswald: Badline will cause to refetch the next charline, and you want to have a badline without that I presume? Why? :D
hehe, there is a neat trick (or rather plan) behind it, yes. I'll tell when the part is released :) if only 7 lines rows possible then its pointless I guess. |
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JackAsser
Registered: Jun 2002
Posts: 2038 |
Quote: hehe, there is a neat trick (or rather plan) behind it, yes. I'll tell when the part is released :) if only 7 lines rows possible then its pointless I guess.
If RC=7 then VC->VCBASE regardless of badline condition, so no, only 7 lines. |
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ChristopherJam
Registered: Aug 2004
Posts: 1423 |
Quoting Oswaldif only 7 lines rows possible then its pointless I guess.
Eh, I used a new instance of row 0 every 5 rasters in Jam Ball 2 to keep my framebuffer size down and thought that was reasonably worthwhile :)
Alternately (assuming you can afford to lose another 60 or so cycles) you could do two badlines at the start of every group of eight and use one charset/bitmap for the first line and another for the remaining seven. |
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