207 lines
4.1 KiB
ArmAsm
207 lines
4.1 KiB
ArmAsm
;*********************************************************
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; *
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; APPLECOMMANDER boot code. *
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; Copyright (c) 2002, Rob Greene *
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; *
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; This code is published under the GPL license. See the *
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; AppleCommander site for license information. *
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; *
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;*********************************************************
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; Assemble this code with the cc65 toolchain:
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;
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; cl65 -t none --start-addr 0x0800 -l AppleCommander-boot.lst AppleCommander-boot.s
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; then copy resulting AppleCommander-boot to:
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; .../src/com/webcodepro/applecommander/storage/AppleCommander-boot.dump
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;
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; Note that this command will hexdump a useful format for pasting and testing...
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; hexdump -e '"08%02.2_ax:" 16/1 "%02x " "\n"' AppleCommander-boot
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;
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; Define as ASCII string with no attributes
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.macro asc Arg
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.repeat .strlen(Arg), I
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.byte .strat(Arg, I) | $80
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.endrep
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.endmacro
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; Define as ASCII string with trailing CR
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.macro asccr Arg
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.repeat .strlen(Arg), I
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.byte .strat(Arg, I) | $80
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.endrep
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.byte $8d
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.endmacro
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.org $0800
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;
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; Zero page variables. Used by Apple ][ ROM routines
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; as well as this code.
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;
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XEND = $2C
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ADDR = $26
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;
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; Keyboard switches
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;
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KEYBOARD = $C000
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KEYCLEAR = $C010
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;
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; Disk ][ interface locations
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;
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MOTOROFF = $C088
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;
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; General Apple ][ ROM locations
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;
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TEXT = $FB2F
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HOME = $FC58
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GR = $FB40
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COLOR = $F864
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HLIN = $F819
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PRINT = $FDF0
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REBOOT = $FAA6
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CALCADDR = $F847
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DELAY = $FCA8
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;
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; Image offset locations (from upper-left).
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; Note that, due to space, the XOFFSET isn't
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; currently used - but, because of the rotating
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; image, it doesn't really matter!
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;
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XOFFSET = 14
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YOFFSET = 13
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;
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; The boot rom (probably $C600) uses the first byte
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; to indicate the number of sectors to load. Normally
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; this is just one sector, so this program is constrained
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; to 256 bytes - just in case of compatibility problems.
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; This also avoids problems with sector ordering.
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; Zero is always zero!
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;
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; Added a little chicanery for the Apple /// to branch around
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; since it starts executing at the zeroeth byte, not the first.
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; This has the effect of setting carry based on machine type.
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;
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.byte $01
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SEC
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BCS $0807 ; The General setup section, below
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JMP $A132 ; Apple /// code to pull in the next sector
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;
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; General setup.
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;
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LDA MOTOROFF,X
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JSR TEXT
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JSR HOME
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JSR GR
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;
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; Draw the AppleCommander logo (well, sorta).
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; DATA1 and DATA2 contain 4 values - the color value,
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; the xstart (start of line), xend (end of line), as
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; well as the Y position.
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;
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LDX #DATA2-DATA1
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LOGO:
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LDA DATA1-1,X
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LSR
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LSR
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LSR
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LSR
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JSR COLOR
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LDA DATA2-1,X
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LSR
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LSR
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LSR
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LSR
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STA XEND
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LDA DATA1-1,X
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AND #$F
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TAY
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LDA DATA2-1,X
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AND #$F
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CLC
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ADC #YOFFSET
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JSR HLIN
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DEX
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BNE LOGO
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;
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; Display AppleCommander message.
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;
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DISPMSG:
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LDA MESSAGE,X
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BEQ WAIT
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JSR PRINT
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INX
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BNE DISPMSG
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;
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; Check for a keypress
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;
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WAIT:
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LDA KEYBOARD
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BPL SETUP
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STA KEYCLEAR
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JMP REBOOT
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;
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; Rotate the screen (isn't that retro)!
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;
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SETUP:
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LDX #19
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ROTATE:
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TXA
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JSR CALCADDR
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LDY #39
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LDA (ADDR),Y
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PHA
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SHIFT:
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DEY
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LDA (ADDR),Y
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INY
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STA (ADDR),Y
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DEY
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BNE SHIFT
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PLA
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STA (ADDR),Y
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DEX
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BPL ROTATE
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;
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; Introduce a pause between rotations.
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;
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KEYLOOP:
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LDA #$08
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JSR DELAY
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DEX
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BNE KEYLOOP
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BEQ WAIT
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;
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; The image data codes the upper nybble with one
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; value and the lower nybble with the second value
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; in an effort to conserve space. Thus, 17 HLINs
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; are stored in 34 bytes instead of 68.
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;
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; DATA1 consists of color and x1 (start) position.
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;
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DATA1:
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.byte $C8, $C7, $C6, $C3, $C8, $C2 ; green
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.byte $D1, $D1 ; yellow
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.byte $90, $90 ; orange
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.byte $10, $10 ; red
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.byte $31, $31 ; purple
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.byte $62, $63, $68 ; blue
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;
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; DATA2 consists of x2 (end) and y position.
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;
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DATA2:
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.byte $90, $81, $72, $53, $B3, $C4
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.byte $D5, $D6
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.byte $C7, $B8
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.byte $B9, $CA
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.byte $DB, $DC
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.byte $CD, $5E, $BE
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;
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; Text message to display at bottom of screen.
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;
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MESSAGE:
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asccr "APPLECOMMANDER CREATED THIS DISK"
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asccr "VISIT APPLECOMMANDER.GITHUB.IO"
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.byte $8d
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asc "INSERT ANOTHER DISK AND PRESS ANY KEY"
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.byte $00
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