C64 poke characters
This means that screen ram is filled with values 12,05,01,04,19,2E.
It is a bitvalue of one of VIC2's control registers.Oups the screen is completly broken now, and we can see some pixels blinking in the first rows of display.Taking a closer look at a game at assembly language level will allow professionals to quickly find what could be left to cheat.This results is a construct such.Character ROM, this font or character generator is an area of the C64 memory used by VIC II to draw pixels of an individual character.But wait, I didnt tell you anything about this display mode colors At first sight, one could believe that HiRes bitmap display is limited to 2 colors (one for background, one for foreground) and only the bitmap memory determines the pixel state on screen.
This should give you an hint about the way pixels data are stored in a bitmap Bitmap data are divided in 88 pixels blocks, where data is encoded the same way as in character ROM.
The 16-bit address comes out in a zeropage pointer, and so the short poke handling routine (a mere 9 bytes long) simply sets the Y index register to zero and uses an indirect indexed STA to store the given byte in the designated address.
Not a bit in a charactervalue or something.How to clear bitmap With defaults settings (i.e after a C64 reset VIC II is using addresses 0000-1FFF for its bitmap.So, in this default memory configuration, our basic program displayed the 8 first bytes of I/O area.Second char at column 1, paire de 4 poker row 0 is located at address 0401 (1025 in decimal).Extended character mode places a limit on the number of different characters you can display, however.Examples, pOKE 53280,1, the screen frame color will be changed into white.