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Mace
Registered: May 2002
Posts: 1799 |
Ghostbyte / garbage / $3FFF
Discussion about the ghostbyte in the comment of Aliens:
Quoting Jammerso for what extent can i control this 'garbage'? in terms of chars and colours.
The ghostbyte is always black.
It occurs in the upper and lower border, when opened, but also in the 'void' that is created with an FLD routine.
If you want that effect as seen in Aliens, you have to write values to $3FFF in a raster routine.
The byte is repeated over the entire width and height of the borders, as the patterns shows.
BTW, I can't remember ever seeing a 'split raster' in $3FFF...
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Ksubi
Account closed
Registered: Nov 2007
Posts: 87 |
My favourite ghost byte piece of code from 1987: Gauntlet the intro by the Cult is simple and cool. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
I think Graham made the coolest application of it so far (C128 only though) in RFO - The VIC experience. If you open the top/bottom border and disable the screen at the same time u get the classic sprites+3fff without chars screen. On a C128 in 2Mhz mode the VIC will never issue any memory reads so the $3fff-gfx every VIC-cycle is now instead what was left on the bus, i.e. the bytes that was read by the CPU. So, by using 2c op-codes, like f.e. LDA #$xx u can indirectly alter the $3fff gfx every VIC-cycles by simply align the CPU-read of the immediate value and the VIC. Kinda cool! :) |
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Mace
Registered: May 2002
Posts: 1799 |
JackAsser... can you translate that to a language I understand, please? :D |
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Danzig
Registered: Jun 2002
Posts: 440 |
Quote: and to further extend this exciting coder dick size compo: I have found the ghostbyte myself when playing with a ripped fld routine being 14 years old, even made these pattern effects with it. anyone has better bets? :)
you explored it yesterday? that makes dick size * -1 ;) |
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Zyron
Registered: Jan 2002
Posts: 2381 |
Quote: JackAsser... can you translate that to a language I understand, please? :D
You can make cool effect! ;) |
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Hein
Registered: Apr 2004
Posts: 954 |
There is also simple but practical use, I used it in The Good, the Bad and the Ugly with split raster to create a lovely black rectangle in the top border. |
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Mace
Registered: May 2002
Posts: 1799 |
LOL @ Zyron :-) |
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Krill
Registered: Apr 2002
Posts: 2980 |
Mace: You do lda #$55 : lda #$f0 : lda #$0f and it shows this pattern: .*.*.*.*****........**** - fill a whole screen with it plus sideborder sprites and you have full-screen hires. |
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Mace
Registered: May 2002
Posts: 1799 |
@ Krill: ah, I see! Interesting. |
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Monte Carlos
Registered: Jun 2004
Posts: 359 |
Did you know, that the ghostbyte
in multicolor mode is behind / before
Sprites dependent on $d01d and the pixel combination
of a ghostbyte double pixel?
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