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Bizzmo
Account closed
Registered: Mar 2005
Posts: 82 |
Video bank selection...
I'm in the process of re-learning to code! After 15 years or so I'm more than a little rusty so please excuse any silly questions!
I'm planning a little game, which is currently using the following memory configuration. (At the moment all this is stuffed at $C000. I want to use a bank without a ROM image so I can have as much memory available for graphics.
Data is currently at these offsets:
+$0000 - Screen Buffer 1
+$0400 - Screen Buffer 2
+$0800 - Character Set
+$1000 - Sprites Definitions...
Is this going to cause me a problem? Trying to load data to $D000 causes WinVice to do strange things! ;-)
Any tips would be appreciated!
Bizz.
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iopop
Registered: Dec 2001
Posts: 317 |
To calculate the value to put into $D018 I ususally use this formula:
lownibble = (char_mem-((3-gfx_bank)*$4000))/$0400
hignibble = (scr_mem-((3-gfx_bank)*$4000))/$0400
Where char_mem and scr_mem have to be at $0800 respectively $0400 boundaries and gfx_bank = {0 .. 3}. |
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Stryyker
Registered: Dec 2001
Posts: 468 |
I experienced $01 issues with loading and saving. I was patient at the time with no carts to freeze or reset. I would use the standard ROM routines then make a drink :)
I would read a byte, SEI, $01=$34, write data to memory, $01=$37, continue until end of file. |
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White Flame
Registered: Sep 2002
Posts: 136 |
Here's my $d018/$dd00 setup for use in cc65. Set CharBase and FontBase to their full addresses, and everything works out. Just make sure they're in the same 16k bank. :)
; Set char/font pointers
lda #((CharBase >> 6) & $f0) | ((FontBase >> 10) & $0e)
sta $d018
; Set VIC bank
lda # ((CharBase ^ $ffff) >> 14)
sta $dd00 |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Growing beards are we? =D |
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White Flame
Registered: Sep 2002
Posts: 136 |
Actually, I've kept them trimmed to the same length for years now. :)= |
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yago
Registered: May 2002
Posts: 333 |
My 0.02 regarding VIC-Memorysettings:
#include <macros/graphics.inc>
vicbnk=$C000
SETVICBANK(vicbnk)
lda#SCREENFONT($C000-vicbnk,$C800-vicbnk)
sta vic.mem
where graphics.inc has:
#ifdef DLOAD
#begindef SETVICBANK(address)
lda #0
sta cia2
lda #($3f^((address/16384)^3))
sta cia2|2
#enddef
#else
#begindef SETVICBANK(address)
lda #(address/16384)^3
sta cia2
#enddef
#endif
and
#define SCREENFONT(screen,font) ((screen)/64)|((font)/1024)| %?
and vic.mem is $D018
--
If everything is worth money
money is worth nothing |
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Frantic
Registered: Mar 2003
Posts: 1648 |
"lda #($3f^((address/16384)^3))"?
I have to ask: Do you actually think in decimal numbers when coding? ...or do you translate $4000 to 16384 when typing the code? :)
I hate it when people use decimal notation instead of hexadecimal ;) (no offence whatsoever, it's not YOU I hate, just this phenomenon.). I think I will never understand the reasons behind it.. I suspect it's ununderstandable in principle. ;) |
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Oswald
Registered: Apr 2002
Posts: 5094 |
autoboy: if you started doing sprites, replacing charsets and stuff in basic, you would be also used to decimal notation :) took me years to learn all the addys in hex.
btw, bank, screen and cset selection is way too simple. I simply use
lda %xxxxxxxx
sta whatever
needs 5 seconds of thinking instead of overcomplicated adress translations. |
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Frantic
Registered: Mar 2003
Posts: 1648 |
Oswald: Ok, so first you initialize a zeropage memory location with the correct $d018 value? (just kidding.. Nerd laughter: HIE HEHE HAHE HI HAHE HEAI HIE HEII HI I AEE HEEE ;)
Anyway.. I guess you hinted at a possible explanation for the decimal-phenomenon. Never thought of that. Probably because I never coded much BASIC. |
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yago
Registered: May 2002
Posts: 333 |
Yeah, Oswald is right. The partly-hexadecimal, partly-decimal scheme is due to historical reasons.
Although "only" one-liners, these beasts evolve over the years, sometimes having old basic-stuff in it.
As I read through this Thread, there are indeed much better (faster+shorter) ways then "/16384", especially ">>14" or ">>$e" in hexadecimal ;-)
And to answer your question, autoboy: When seeing the Number 16384, my Mind switches instantly to hexadecimal and thinks: Cool, thats $4000 !
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