base:code_frame_for_16_kb_crt-images
Raw Frame for Generic 16 KB cart images
; raw frame for generic 16 KB cartridge images ; v 1.0 enthusi 04/2012 ; this 16 KB Cartridge framework was written for http://www.rgcd.co.uk ; feel free to use/change this code and give credits :) ; you will find this document also at http://codebase64.org ; this is a VERY simple but efficient approach, you can make more ; sophisticated usage of ROM using an own depacker routine etc.... ; sources are in XA format but no special features are used ; I strongly recommend the usage of cartconv which comes with vice ; you can as well set up your own crt-header, which will look ; more or less like this:
;.asc "C64 CARTRIDGE " ;.byte $00,$00 ;header length ;.byte $00,$40 ;header length ;.word $0001 ;version ;.word $0000 ;crt type ;.byte $00 ;extrom line ;.byte $00 ;game line ;.byte $00,$00,$00,$00,$00,$00 ;unused ;.asc "MY NAME" ;name ;.dsb ($0040-name),0 ;;chip packets ;.asc "CHIP" ;.byte $00,$00,$40,$10 ;chip length? ;.byte $00,$00 ;chip type ;.byte $00,$00 ;bank ;.byte $80,$00 ;adress ;.byte $40,$00 ;length ;ROM part follows...
The following is for creating a .bin file of 16384 Bytes length as you would burn it onto EPROM, or to use as input for cartconv and alike.
;---------------------------------------------------------- ; example usage ; xa frame.asm -o frame.bin ; cartconv -t normal -i frame.bin -n 'my cart' -o frame.crt ; x64 -cartcrt frame.crt ;---------------------------------------------------------- ;no load-adress for bin-file, so no header here *=$8000 .word launcher ;cold start .word launcher ;warm start .byte $c3 ;c .byte $c2 ;b .byte $cd ;m .byte $38 ;8 .byte $30 ;0 launcher stx $d016 jsr $fda3 ;prepare irq jsr $fd50 ;init memory jsr $fd15 ;init i/o jsr $ff5b ;init video ;make sure this sets up everything you need, ;the calls above are probably sufficient ldx #$fb txs ;set up starting code outside of cartridge-area move_starter ldx #(starter_end-starter_start) loop1 lda starter_start,x sta $100,x dex bpl loop1 jmp $100 ;--------------------------------- starter_start ldx #$40 ;64 pages = 256 * 64 = 16384 Bytes ldy #0 loop src lda exomized_data,y dst sta $801,y iny bne loop inc src+2-starter_start+$100 inc dst+2-starter_start+$100 dex bpl loop ;make sure settings for $01 and IRQ etc are correct for your code ;remember THIS table from AAY64: ; Bit+-------------+-----------+------------+ ; 210| $8000-$BFFF |$D000-$DFFF|$E000-$FFFF | ; +---+---+-------------+-----------+------------+ ; | 7 |111| Cart.+Basic | I/O | Kernal ROM | ; +---+---+-------------+-----------+------------+ ; | 6 |110| RAM | I/O | Kernal ROM | ; +---+---+-------------+-----------+------------+ ; | 5 |101| RAM | I/O | RAM | ; +---+---+-------------+-----------+------------+ ; | 4 |100| RAM | RAM | RAM | ; +---+---+-------------+-----------+------------+ ; | 3 |011| Cart.+Basic | Char. ROM | Kernal ROM | ; +---+---+-------------+-----------+------------+ ; | 2 |010| RAM | Char. ROM | Kernal ROM | ; +---+---+-------------+-----------+------------+ ; | 1 |001| RAM | Char. ROM | RAM | ; +---+---+-------------+-----------+------------+ ; | 0 |000| RAM | RAM | RAM | ; +---+---+-------------+-----------+------------+ lda #$35 ;cart is always on instead of BASIC unless it can be switched off via software sta $01 jmp $80d ;for exomizer, i.e. starter_end ;---------------------------------- exomized_data .bin 2,0,"data.exo" ;syntax for exomizer 2.0.1: ;exomizer sfx sys game.prg -o data.exo main_file_end ;fill up full $4000 bytes for bin file ($c000-$8000=$4000) .dsb ($c000-main_file_end),0
base/code_frame_for_16_kb_crt-images.txt · Last modified: 2015-04-17 04:30 by 127.0.0.1