Subject: Re: Re[2]: [stella] Bank-switching From: "Andy Mucho" <andy@xxxxxxxxxxxxxxxxxxxx> Date: Sat, 2 Aug 2003 10:07:58 +0100 |
Vlad Pylin wrote: > I want a cartridge 256K with 128 banks of 2K each. > I know that the upper 2K of the address space is the last 2K of the ROM and > the lower 2K is the selectable bank. Writing to 003Fh selects this bank. It > is possible to access the TIA at 0040-007fh though (instead of the usual > 0000-003fh). > > Please, write me how can I use it in my code and compile with DASM, because > I don't find that in the archives. > processor 6502 include "VCS3F.h" ;; ;; This lives in Bank 0.. ;; SEG ORG $00000 ; < Bank starts at 0k in ROM RORG $F000 somedata: .byte 1,2,3,4,5,6,7,8 ;; This lives in Bank 2.. SEG ORG $00800 ; < Bank starts at 2K in ROM RORG $F000 somecode: rts ;; ;; This lives in Bank 64.. ;; SEG ORG $20000 ; < Bank start at 128K in ROM RORG $F000 somemorecode: inx stx COLUBK jmp somemorecode ;; ;; This lives in Bank 96.. ;; SEG ORG $30000 ; < Bank start at 192K in ROM RORG $F000 somemorecode: inx stx COLUBK jmp somemorecode ;; ;; The boot/constant bank at $F800 which lvies in Bank 127 ;; SEG ORG $3F800 RORG $F800 RESET: ;; ;; Bank in bank 64 in $F000 ;; lda #$20000/$0800 sta $3F jsr somemorecode ;; ;; Bank in Bank 1 into $F000 ;; lda #$0800/$0800 sta $3F lda SomeData from bank ORG $3FFFA .word RESET .word RESET .word RESET That's just about the way ti works.. SEG ORG $??000 RORG $F000 Are your friends :) andym ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
Current Thread |
---|
|
<- Previous | Index | Next -> |
---|---|---|
Re: [stella] Bank-switching, Thomas Jentzsch | Thread | [stella] Some Background Questions , Eric Ball |
Re: [stella] 2600 Sound, that time , Andy Mucho | Date | [stella] SoundSim code.., Andy Mucho |
Month |