Posted By
gerliczer
on 2012-08-07
12:16:10
|  Re: Searchin' for a char editor...
George,
If you do it in the sequence you wrote, it is no wonder that you get all zeroes. First you load the characters into the RAM from $3800 up to $3FFF, then with the GRAPHIC 3,1 command you fill the memory from $2000 to $3F3F with zeroes. You must definitely change the character generator's address.
If this program is intended to run on machines with more than 16kB RAM, then you could place it at $1000 or $1800, because the GRAPHIC command relocates the BASIC program behind the graphic memory but you _must_ do that after issuing the screen mode change command. If this program should run on an unexpanded C=16, then tough luck. I don't think that it is possible without any assembly magic.
Changing the address of the charset is not too hard. You must change the load address of the file which are its first two bytes. Now it is $00 $38. You have to change the second byte to the address you find most appropriate. One more thing. Do not change those zero page values that the Graphics Master instruction suggests to modify if you put the chargen into the $1000-$1FFF area.
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