Subject: Re: [stella] Reading the Booster Grip From: tjentzsch@xxxxxx Date: Wed, 13 Feb 2002 11:50:42 +0100 |
I wrote: > I'll disassemble Omega Race soon... Ok, here is what I found (this code is placed just before the begin of VSYNC): lda SWCHA and #$cc ; clear up and down bits ldy INPT0 bpl Lf25b ora #$10 ; enable up bit Lf25b: ldy INPT1 bmi Lf263 ldy INPT4 ; fire button is also an option here bmi Lf265 Lf263: ora #$20 ; enable down bit Lf265: ...about the same code is repeated for the other joystick port depending on P1 difficulty Then directly follows the VSYNC block (with a bit unusual timers): lda #$82 sta WSYNC sta VSYNC sta VBLANK ; sets bits 1 and 7 lda $0285 lda #$2a sta $029d ; about the same as TIM8T Lf29a: lda $0285 bpl Lf29a ; wait for timer (5 scan lines) lda #$00 sta WSYNC sta VSYNC And at the end of VBLANK the bits 1 and 7 are cleared again. I can't see any new informations in this code, perhaps others will know better. Attached is a DiStella configuration file for the last 4K block, so you can disassemble it yourself. Have fun! Thomas _______________________________________________________ Thomas Jentzsch | *** Every bit is sacred ! *** tjentzsch at web dot de | ______________________________________________________________________________ Seien Sie dabei und sichern Sie sich 100% Leistung, 100% Prämie und 100% Zufriedenheit. Jetzt unter http://club.web.de/?mc=021105
Attachment:
omega3.cfg
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