Mats wrote:
If you really want to run it on a real ATARI computer I can tell you that with:
Code:
*= $FFFA
.word Start ; NMI
.word Start ; RESET
.word Start ; IRQ
nothing will work, the ATARI will be completly dead!
The reset vector in $FFFC,$FFFD has to point to an adequate boot sequence and also the IRQ vector in $FFFE,$FFFF is certainly needed for hardware interrupts and has to point to completly different code then what you have following label "Start"!. If it at all should possible for a "user" to write his own programs for an ATARI computer there must be some "Application Program Interfaces" foreseen in the ATARI operating system. Otherwise you have to write the complete operating system yourself including management of screen, keyboard etc.
The
Code:
include vcs.h
include macro.h
must contain a lot of stuff as your code (without this) is full of undefined labels/symbols. From where does this "include code" come and from where the idea that ATARI application programs can be written with this approach overwriting the original operating system resident in ROM? At least the top of the ROM is part of the operating system! Application programs have to reside in RAM/ROM not used by the operating system and control to the application program has to be given from the operating system in the way foreseen by the system designer!
For a Commodore this is done with BASIC command "SYS".
OK, I don't understand enough to know what you're talking about. The code
Code:
*= $FFFA
.word Start ; NMI
.word Start ; RESET
.word Start ; IRQ
is in all the examples I have been working with, and it works on the assembler and the atari emulators. Here is the code from the include files:
Code:
; VCS.H
; Version 1.05, 13/November/2003
VERSION_VCS = 105
; THIS IS A PRELIMINARY RELEASE OF *THE* "STANDARD" VCS.H
; THIS FILE IS EXPLICITLY SUPPORTED AS A DASM-PREFERRED COMPANION FILE
; PLEASE DO *NOT* REDISTRIBUTE THIS FILE!
;
; This file defines hardware registers and memory mapping for the
; Atari 2600. It is distributed as a companion machine-specific support package
; for the DASM compiler. Updates to this file, DASM, and associated tools are
; available at at http://www.atari2600.org/dasm
;
; Many thanks to the original author(s) of this file, and to everyone who has
; contributed to understanding the Atari 2600. If you take issue with the
; contents, or naming of registers, please write to me (atari2600@taswegian.com)
; with your views. Please contribute, if you think you can improve this
; file!
;
; Latest Revisions...
; 1.05 13/NOV/2003 - Correction to 1.04 - now functions as requested by MR.
; - Added VERSION_VCS equate (which will reflect 100x version #)
; This will allow conditional code to verify VCS.H being
; used for code assembly.
; 1.04 12/NOV/2003 Added TIA_BASE_WRITE_ADDRESS and TIA_BASE_READ_ADDRESS for
; convenient disassembly/reassembly compatibility for hardware
; mirrored reading/writing differences. This is more a
; readability issue, and binary compatibility with disassembled
; and reassembled sources. Per Manuel Rotschkar's suggestion.
; 1.03 12/MAY/2003 Added SEG segment at end of file to fix old-code compatibility
; which was broken by the use of segments in this file, as
; reported by Manuel Polik on [stella] 11/MAY/2003
; 1.02 22/MAR/2003 Added TIMINT($285)
; 1.01 Constant offset added to allow use for 3F-style bankswitching
; - define TIA_BASE_ADDRESS as $40 for Tigervision carts, otherwise
; it is safe to leave it undefined, and the base address will
; be set to 0. Thanks to Eckhard Stolberg for the suggestion.
; Note, may use -DLABEL=EXPRESSION to define TIA_BASE_ADDRESS
; - register definitions are now generated through assignment
; in uninitialised segments. This allows a changeable base
; address architecture.
; 1.0 22/MAR/2003 Initial release
;-------------------------------------------------------------------------------
; TIA_BASE_ADDRESS
; The TIA_BASE_ADDRESS defines the base address of access to TIA registers.
; Normally 0, the base address should (externally, before including this file)
; be set to $40 when creating 3F-bankswitched (and other?) cartridges.
; The reason is that this bankswitching scheme treats any access to locations
; < $40 as a bankswitch.
IFNCONST TIA_BASE_ADDRESS
TIA_BASE_ADDRESS = 0
ENDIF
; Note: The address may be defined on the command-line using the -D switch, eg:
; dasm.exe code.asm -DTIA_BASE_ADDRESS=$40 -f3 -v5 -ocode.bin
; *OR* by declaring the label before including this file, eg:
; TIA_BASE_ADDRESS = $40
; include "vcs.h"
; Alternate read/write address capability - allows for some disassembly compatibility
; usage ; to allow reassembly to binary perfect copies). This is essentially catering
; for the mirrored ROM hardware registers.
; Usage: As per above, define the TIA_BASE_READ_ADDRESS and/or TIA_BASE_WRITE_ADDRESS
; using the -D command-line switch, as required. If the addresses are not defined,
; they defaut to the TIA_BASE_ADDRESS.
IFNCONST TIA_BASE_READ_ADDRESS
TIA_BASE_READ_ADDRESS = TIA_BASE_ADDRESS
ENDIF
IFNCONST TIA_BASE_WRITE_ADDRESS
TIA_BASE_WRITE_ADDRESS = TIA_BASE_ADDRESS
ENDIF
;-------------------------------------------------------------------------------
SEG.U TIA_REGISTERS_WRITE
ORG TIA_BASE_WRITE_ADDRESS
; DO NOT CHANGE THE RELATIVE ORDERING OF REGISTERS!
VSYNC ds 1 ; $00 0000 00x0 Vertical Sync Set-Clear
VBLANK ds 1 ; $01 xx00 00x0 Vertical Blank Set-Clear
WSYNC ds 1 ; $02 ---- ---- Wait for Horizontal Blank
RSYNC ds 1 ; $03 ---- ---- Reset Horizontal Sync Counter
NUSIZ0 ds 1 ; $04 00xx 0xxx Number-Size player/missle 0
NUSIZ1 ds 1 ; $05 00xx 0xxx Number-Size player/missle 1
COLUP0 ds 1 ; $06 xxxx xxx0 Color-Luminance Player 0
COLUP1 ds 1 ; $07 xxxx xxx0 Color-Luminance Player 1
COLUPF ds 1 ; $08 xxxx xxx0 Color-Luminance Playfield
COLUBK ds 1 ; $09 xxxx xxx0 Color-Luminance Background
CTRLPF ds 1 ; $0A 00xx 0xxx Control Playfield, Ball, Collisions
REFP0 ds 1 ; $0B 0000 x000 Reflection Player 0
REFP1 ds 1 ; $0C 0000 x000 Reflection Player 1
PF0 ds 1 ; $0D xxxx 0000 Playfield Register Byte 0
PF1 ds 1 ; $0E xxxx xxxx Playfield Register Byte 1
PF2 ds 1 ; $0F xxxx xxxx Playfield Register Byte 2
RESP0 ds 1 ; $10 ---- ---- Reset Player 0
RESP1 ds 1 ; $11 ---- ---- Reset Player 1
RESM0 ds 1 ; $12 ---- ---- Reset Missle 0
RESM1 ds 1 ; $13 ---- ---- Reset Missle 1
RESBL ds 1 ; $14 ---- ---- Reset Ball
AUDC0 ds 1 ; $15 0000 xxxx Audio Control 0
AUDC1 ds 1 ; $16 0000 xxxx Audio Control 1
AUDF0 ds 1 ; $17 000x xxxx Audio Frequency 0
AUDF1 ds 1 ; $18 000x xxxx Audio Frequency 1
AUDV0 ds 1 ; $19 0000 xxxx Audio Volume 0
AUDV1 ds 1 ; $1A 0000 xxxx Audio Volume 1
GRP0 ds 1 ; $1B xxxx xxxx Graphics Register Player 0
GRP1 ds 1 ; $1C xxxx xxxx Graphics Register Player 1
ENAM0 ds 1 ; $1D 0000 00x0 Graphics Enable Missle 0
ENAM1 ds 1 ; $1E 0000 00x0 Graphics Enable Missle 1
ENABL ds 1 ; $1F 0000 00x0 Graphics Enable Ball
HMP0 ds 1 ; $20 xxxx 0000 Horizontal Motion Player 0
HMP1 ds 1 ; $21 xxxx 0000 Horizontal Motion Player 1
HMM0 ds 1 ; $22 xxxx 0000 Horizontal Motion Missle 0
HMM1 ds 1 ; $23 xxxx 0000 Horizontal Motion Missle 1
HMBL ds 1 ; $24 xxxx 0000 Horizontal Motion Ball
VDELP0 ds 1 ; $25 0000 000x Vertical Delay Player 0
VDELP1 ds 1 ; $26 0000 000x Vertical Delay Player 1
VDELBL ds 1 ; $27 0000 000x Vertical Delay Ball
RESMP0 ds 1 ; $28 0000 00x0 Reset Missle 0 to Player 0
RESMP1 ds 1 ; $29 0000 00x0 Reset Missle 1 to Player 1
HMOVE ds 1 ; $2A ---- ---- Apply Horizontal Motion
HMCLR ds 1 ; $2B ---- ---- Clear Horizontal Move Registers
CXCLR ds 1 ; $2C ---- ---- Clear Collision Latches
;-------------------------------------------------------------------------------
SEG.U TIA_REGISTERS_READ
ORG TIA_BASE_READ_ADDRESS
; bit 7 bit 6
CXM0P ds 1 ; $00 xx00 0000 Read Collision M0-P1 M0-P0
CXM1P ds 1 ; $01 xx00 0000 M1-P0 M1-P1
CXP0FB ds 1 ; $02 xx00 0000 P0-PF P0-BL
CXP1FB ds 1 ; $03 xx00 0000 P1-PF P1-BL
CXM0FB ds 1 ; $04 xx00 0000 M0-PF M0-BL
CXM1FB ds 1 ; $05 xx00 0000 M1-PF M1-BL
CXBLPF ds 1 ; $06 x000 0000 BL-PF -----
CXPPMM ds 1 ; $07 xx00 0000 P0-P1 M0-M1
INPT0 ds 1 ; $08 x000 0000 Read Pot Port 0
INPT1 ds 1 ; $09 x000 0000 Read Pot Port 1
INPT2 ds 1 ; $0A x000 0000 Read Pot Port 2
INPT3 ds 1 ; $0B x000 0000 Read Pot Port 3
INPT4 ds 1 ; $0C x000 0000 Read Input (Trigger) 0
INPT5 ds 1 ; $0D x000 0000 Read Input (Trigger) 1
;-------------------------------------------------------------------------------
SEG.U RIOT
ORG $280
; RIOT MEMORY MAP
SWCHA ds 1 ; $280 Port A data register for joysticks:
; Bits 4-7 for player 1. Bits 0-3 for player 2.
SWACNT ds 1 ; $281 Port A data direction register (DDR)
SWCHB ds 1 ; $282 Port B data (console switches)
SWBCNT ds 1 ; $283 Port B DDR
INTIM ds 1 ; $284 Timer output
TIMINT ds 1 ; $285
; Unused/undefined registers ($285-$294)
ds 1 ; $286
ds 1 ; $287
ds 1 ; $288
ds 1 ; $289
ds 1 ; $28A
ds 1 ; $28B
ds 1 ; $28C
ds 1 ; $28D
ds 1 ; $28E
ds 1 ; $28F
ds 1 ; $290
ds 1 ; $291
ds 1 ; $292
ds 1 ; $293
TIM1T ds 1 ; $294 set 1 clock interval
TIM8T ds 1 ; $295 set 8 clock interval
TIM64T ds 1 ; $296 set 64 clock interval
T1024T ds 1 ; $297 set 1024 clock interval
;-------------------------------------------------------------------------------
; The following required for back-compatibility with code which does not use
; segments.
SEG
; EOF
and
Code:
; MACRO.H
; Version 1.06, 3/SEPTEMBER/2004
VERSION_MACRO = 106
;
; THIS FILE IS EXPLICITLY SUPPORTED AS A DASM-PREFERRED COMPANION FILE
; PLEASE DO *NOT* REDISTRIBUTE MODIFIED VERSIONS OF THIS FILE!
;
; This file defines DASM macros useful for development for the Atari 2600.
; It is distributed as a companion machine-specific support package
; for the DASM compiler. Updates to this file, DASM, and associated tools are
; available at at http://www.atari2600.org/dasm
;
; Many thanks to the people who have contributed. If you take issue with the
; contents, or would like to add something, please write to me
; (atari2600@taswegian.com) with your contribution.
;
; Latest Revisions...
;
; 1.06 03/SEP/2004 - nice revision of VERTICAL_BLANK (Edwin Blink)
; 1.05 14/NOV/2003 - Added VERSION_MACRO equate (which will reflect 100x version #)
; This will allow conditional code to verify MACRO.H being
; used for code assembly.
; 1.04 13/NOV/2003 - SET_POINTER macro added (16-bit address load)
;
; 1.03 23/JUN/2003 - CLEAN_START macro added - clears TIA, RAM, registers
;
; 1.02 14/JUN/2003 - VERTICAL_SYNC macro added
; (standardised macro for vertical synch code)
; 1.01 22/MAR/2003 - SLEEP macro added.
; - NO_ILLEGAL_OPCODES switch implemented
; 1.0 22/MAR/2003 Initial release
; Note: These macros use illegal opcodes. To disable illegal opcode usage,
; define the symbol NO_ILLEGAL_OPCODES (-DNO_ILLEGAL_OPCODES=1 on command-line).
; If you do not allow illegal opcode usage, you must include this file
; *after* including VCS.H (as the non-illegal opcodes access hardware
; registers and require them to be defined first).
; Available macros...
; SLEEP n - sleep for n cycles
; VERTICAL_SYNC - correct 3 scanline vertical synch code
; CLEAN_START - set machine to known state on startup
; SET_POINTER - load a 16-bit absolute to a 16-bit variable
;-------------------------------------------------------------------------------
; SLEEP duration
; Original author: Thomas Jentzsch
; Inserts code which takes the specified number of cycles to execute. This is
; useful for code where precise timing is required.
; ILLEGAL-OPCODE VERSION DOES NOT AFFECT FLAGS OR REGISTERS.
; LEGAL OPCODE VERSION MAY AFFECT FLAGS
; Uses illegal opcode (DASM 2.20.01 onwards).
MAC SLEEP ;usage: SLEEP n (n>1)
.CYCLES SET {1}
IF .CYCLES < 2
ECHO "MACRO ERROR: 'SLEEP': Duration must be > 1"
ERR
ENDIF
IF .CYCLES & 1
IFNCONST NO_ILLEGAL_OPCODES
nop 0
ELSE
bit VSYNC
ENDIF
.CYCLES SET .CYCLES - 3
ENDIF
REPEAT .CYCLES / 2
nop
REPEND
ENDM
;-------------------------------------------------------------------------------
; VERTICAL_SYNC
; revised version by Edwin Blink -- saves bytes!
; Inserts the code required for a proper 3 scanline vertical sync sequence
; Note: Alters the accumulator
; OUT: A = 0
MAC VERTICAL_SYNC
lda #%1110 ; each '1' bits generate a VSYNC ON line (bits 1..3)
.VSLP1 sta WSYNC ; 1st '0' bit resets Vsync, 2nd '0' bit exit loop
sta VSYNC
lsr
bne .VSLP1 ; branch until VYSNC has been reset
ENDM
;-------------------------------------------------------------------------------
; CLEAN_START
; Original author: Andrew Davie
; Standardised start-up code, clears stack, all TIA registers and RAM to 0
; Sets stack pointer to $FF, and all registers to 0
; Sets decimal mode off, sets interrupt flag (kind of un-necessary)
; Use as very first section of code on boot (ie: at reset)
; Code written to minimise total ROM usage - uses weird 6502 knowledge :)
MAC CLEAN_START
sei
cld
ldx #0
txa
tay
.CLEAR_STACK dex
txs
pha
bne .CLEAR_STACK ; SP=$FF, X = A = Y = 0
ENDM
;-------------------------------------------------------
; SET_POINTER
; Original author: Manuel Rotschkar
;
; Sets a 2 byte RAM pointer to an absolute address.
;
; Usage: SET_POINTER pointer, address
; Example: SET_POINTER SpritePTR, SpriteData
;
; Note: Alters the accumulator, NZ flags
; IN 1: 2 byte RAM location reserved for pointer
; IN 2: absolute address
MAC SET_POINTER
.POINTER SET {1}
.ADDRESS SET {2}
LDA #<.ADDRESS ; Get Lowbyte of Address
STA .POINTER ; Store in pointer
LDA #>.ADDRESS ; Get Hibyte of Address
STA .POINTER+1 ; Store in pointer+1
ENDM
;-------------------------------------------------------
; BOUNDARY byte#
; Original author: Denis Debro (borrowed from Bob Smith / Thomas)
;
; Push data to a certain position inside a page and keep count of how
; many free bytes the programmer will have.
;
; eg: BOUNDARY 5 ; position at byte #5 in page
__DASM__TOTAL_FREE_MEMORY SET 0
.FREE_BYTES SET 0
MAC BOUNDARY
REPEAT 256
IF <. % {1} = 0
MEXIT
ELSE
.FREE_BYTES SET .FREE_BYTES + 1
.byte $00
ENDIF
REPEND
__DASM__TOTAL_FREE_MEMORY SET __DASM__TOTAL_FREE_MEMORY + .FREE_BYTES
ENDM
; EOF
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