mirror of
https://github.com/michaelcmartin/Ophis.git
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128 lines
4.2 KiB
Plaintext
128 lines
4.2 KiB
Plaintext
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; Register mnemonics for the Atari 2600 VCS
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;
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; Taken from the "Stella Programming Guide", at
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; http://www.alienbill.com/2600/101/docs/stella.html
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; Writable TIA addresses
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.alias VSYNC $00 ; vertical sync set-clear
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.alias VBLANK $01 ; vertical blank set-clear
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.alias WSYNC $02 ; wait for leading edge of horizontal blank
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.alias RSYNC $03 ; reset horizontal sync counter
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.alias NUSIZ0 $04 ; number-size player-missile 0
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.alias NUSIZ1 $05 ; number-size player-missile 1
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.alias COLUP0 $06 ; color-lum player 0
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.alias COLUP1 $07 ; color-lum player 1
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.alias COLUPF $08 ; color-lum playfield
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.alias COLUBK $09 ; color-lum background
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.alias CTRLPF $0A ; control playfield ball size and collisions
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.alias REFP0 $0B ; reflect player 0
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.alias REFP1 $0C ; reflect player 1
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.alias PF0 $0D ; playfield register byte 0
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.alias PF1 $0E ; playfield register byte 1
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.alias PF2 $0F ; playfield register byte 2
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.alias RESP0 $10 ; reset player 0
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.alias RESP1 $11 ; reset player 1
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.alias RESM0 $12 ; reset missile 0
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.alias RESM1 $13 ; reset missile 1
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.alias RESBL $14 ; reset ball
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.alias AUDC0 $15 ; audio control 0
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.alias AUDC1 $16 ; audio control 1
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.alias AUDF0 $17 ; audio frequency 0
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.alias AUDF1 $18 ; audio frequency 1
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.alias AUDV0 $19 ; audio volume 0
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.alias AUDV1 $1A ; audio volume 1
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.alias GRP0 $1B ; Graphics player 0
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.alias GRP1 $1C ; Graphics player 1
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.alias ENAM0 $1D ; Graphics enable missile 0
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.alias ENAM1 $1E ; Graphics enable missile 1
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.alias ENABL $1F ; Graphics enable ball
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.alias HMP0 $20 ; horizontal motion player 0
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.alias HMP1 $21 ; horizontal motion player 1
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.alias HMM0 $22 ; horizontal motion missile 0
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.alias HMM1 $23 ; horizontal motion missile 1
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.alias HMBL $24 ; horizontal motion ball
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.alias VDELP0 $25 ; vertical delay player 0
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.alias VDELP1 $26 ; vertical delay player 1
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.alias VDELBL $27 ; vertical delay ball
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.alias RESMP0 $28 ; reset missile 0 to player 0
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.alias RESMP1 $29 ; reset missile 1 to player 1
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.alias HMOVE $2A ; apply horizontal motion
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.alias HMCLR $2B ; clear horizontal motion registers
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.alias CXCLR $2C ; clear collision latches
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; Readable TIA addresses
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.alias CXM0P $00 ; read collision missile 0 players
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.alias CXM1P $01 ; read collision missile 1 players
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.alias CXP0FB $02 ; read collision player 0 playfield/ball
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.alias CXP1FB $03 ; read collision player 1 playfield/ball
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.alias CXM0FB $04 ; read collision missile 0 playfield/ball
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.alias CXM1FB $05 ; read collision missile 1 playfield/ball
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.alias CXBLPF $06 ; read collision ball playfield
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.alias CXPPMM $07 ; read collision player/player missile/missile
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.alias INPT0 $08 ; read pot port
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.alias INPT1 $09 ; read pot port
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.alias INPT2 $0A ; read pot port
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.alias INPT3 $0B ; read pot port
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.alias INPT4 $0C ; read input
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.alias INPT5 $0D ; read input
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; PIA addresses
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.alias SWCHA $280 ; Port A data register (read/write)
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.alias SWACNT $281 ; Port A data direction register (0=input, 1=output)
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.alias SWCHB $282 ; Port B - console switches (read-only)
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.alias SWBCNT $283 ; Port B data direction register (hardwired to 0)
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.alias INTIM $284 ; Timer output (read only)
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.alias TIM1T $294 ; Set 1-clock interval (838 nsec/interval)
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.alias TIM8T $295 ; Set 8-clock interval (6.7 usec/interval)
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.alias TIM64T $296 ; Set 64-clock interval (53.6 usec/interval
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.alias T1024T $297 ; Set 1025-clock interval (858.2 usec/interval)
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; These macros are adapted from DASM's old macro.h. Credit and description are
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; replicated from there.
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;-------------------------------------------------------------------------------
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; VERTICAL_SYNC
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; Original author: Manuel Polik
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; Inserts the code required for a proper 3 scanline
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; vertical sync sequence
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;
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; Note: Alters the accumulator
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;
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; IN:
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; OUT: A = 1
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.macro vertical'sync
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lda #$02
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sta WSYNC
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sta VSYNC
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sta WSYNC
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sta WSYNC
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lsr
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sta WSYNC
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sta VSYNC
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.macend
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;-------------------------------------------------------------------------------
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; CLEAN_START
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; Original author: Andrew Davie
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; Standardised start-up code, clears stack, all TIA registers and RAM to 0
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; Sets stack pointer to $FF, and all registers to 0
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; Sets decimal mode off, sets interrupt flag (kind of un-necessary)
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; Use as very first section of code on boot (ie: at reset)
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; Code written to minimise total ROM usage - uses weird 6502 knowledge :)
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.macro clean'start
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sei
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cld
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ldx #$00
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txa
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tay
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_clear'stack:
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dex
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txs
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pha
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bne _clear'stack
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.macend
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