Apple-2-SW
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Applecorn
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Applecorn/applecorn.s

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* APPLECORN.S
* (c) Bobbi 2021 GPLv3
*
* Load an Acorn BBC Micro ROM in aux memory and
* Provide an environment where it can run
*
* Assembled with the Merlin 8 v2.58 assembler on Apple II.
* 14-Oct-2021 XF2MAIN, ENTAUX no longer save/restore STRTL/STRTH.
XC ; 65c02
ORG $2000 ; Load addr of loader in main memory
; Clear of first HGR frame buffer
* Monitor routines
BELL EQU $FBDD
PRBYTE EQU $FDDA
COUT1 EQU $FDED
CROUT EQU $FD8E
IDROUTINE EQU $FE1F
HOME EQU $FC58
AUXMOVE EQU $C311
XFER EQU $C314
* Monitor ZP locations
A1L EQU $3C
A1H EQU $3D
A2L EQU $3E
A2H EQU $3F
A3L EQU $40
A3H EQU $41
A4L EQU $42
A4H EQU $43
* Other ZP locations
ISRL EQU $02 ; Used for ISR only
ISRH EQU $03 ; Used for ISR only
SHRZP EQU $56 ; 25 bytes, persistent, SHR code only
TMPZP EQU $56+25 ; Temp scratch space for routines
* Used by XFER
STRTL EQU $3ED
STRTH EQU $3EE
* Apple II BREAK vector
BREAKV EQU $3F0
* Reset vector (2 bytes + 1 byte checksum)
RSTV EQU $3F2
PWRDUP EQU $3F4
* IRQ vector
A2IRQV EQU $3FE
* ProDOS Global Page equates
* MLI entry point
MLI EQU $BF00
* Device Addresses
DEVADR01 EQU $BF10
DEVADR32 EQU $BF26
* Device List
DEVNUM EQU $BF30
DEVCNT EQU $BF31
DEVLST EQU $BF32
* Date & time
PRODOSDATE EQU $BF90
PRODOSTIME EQU $BF92
* Machine ID byte
MACHID EQU $BF98
* Versioning bytes
IBAKVER EQU $BFFC
IVERSION EQU $BFFD
* System BitMap locations
P8BMAP0007 EQU $BF58
P8BMAP080F EQU $BF59
P8BMAP2027 EQU $BF5C
P8BMAP282F EQU $BF5D
P8BMAP3037 EQU $BF5E
P8BMAP383F EQU $BF5F
*Hardware I/O locations
KEYBOARD EQU $C000
80STOREOFF EQU $C000
80STOREON EQU $C001 ; Currently not used
RDMAINRAM EQU $C002
RDCARDRAM EQU $C003
WRMAINRAM EQU $C004
WRCARDRAM EQU $C005
SETSTDZP EQU $C008
SETALTZP EQU $C009
CLR80VID EQU $C00C
SET80VID EQU $C00D
CLRALTCHAR EQU $C00E
SETALTCHAR EQU $C00F
RDRAMRD EQU $C013
RDRAMWR EQU $C014
KBDSTRB EQU $C010
RDVBL EQU $C019
RD80VID EQU $C01F
TBCOLOR EQU $C022 ; GS-specific, text colour reg
NEWVIDEO EQU $C029 ; GS-specific, new video register
SPKR EQU $C030
CLOCKCTL EQU $C034 ; GS-specific, Clock control register
SHADOW EQU $C035 ; GS-specific, Shadow Register
CYAREG EQU $C036 ; GS-specific, CYA Register
GRON EQU $C050
TEXTON EQU $C051
FULLGR EQU $C052
MIXGRTXT EQU $C053 ; Currently not used
PAGE1 EQU $C054
PAGE2 EQU $C055
LORES EQU $C056 ; Currently not used
HIRES EQU $C057
AN0OFF EQU $C058
AN0ON EQU $C059
AN1OFF EQU $C05A
AN1ON EQU $C05B
AN2OFF EQU $C05C
AN2ON EQU $C05D
AN3OFF EQU $C05E
AN3ON EQU $C05F
BUTTON0 EQU $C061
BUTTON1 EQU $C062
ROMIN EQU $C081
LCBANK1 EQU $C08B
* IO Buffer for reading file (1024 bytes)
IOBUF0 EQU $0C00 ; For loading/saving, OSFILE, *.
IOBUF1 EQU $1000 ; Four open files for langs
IOBUF2 EQU $1400
IOBUF3 EQU $1800
IOBUF4 EQU $1C00
* 512 byte buffer sufficient for one disk block
BLKBUF EQU $9000 ; Can't use $400 as ProDOS uses
BLKBUFEND EQU $9200 ; 'hidden' bytes within screen
* 512 byte buffer for file copy (*COPY)
COPYBUF EQU $9200 ; File copy needs separate buffer
*COPYBUFEND EQU $9400
* Location of FDraw library in main memory
FDRAWADDR EQU $9400
* Location of FDraw library in main memory
FONTADDR EQU $A900
* Address in aux memory where ROM will be loaded
ROMAUXADDR EQU $8000
* Address in aux memory where the MOS shim is located
AUXMOS1 EQU $2000 ; Temp staging area in Aux
EAUXMOS1 EQU $5000 ; End of staging area
AUXMOS EQU $D000 ; Final location in aux LC
* Called by code running in main mem to invoke a
* routine in aux memory
XF2AUX MAC
SEI ; Disable IRQ before XFER
LDX LCBANK1 ; R/W LC RAM, bank 1
LDX LCBANK1
LDX #<]1
STX STRTL
LDX #>]1
STX STRTH
SEC ; Use aux memory
BIT RTSINSTR ; Set V: use alt ZP and LC
JMP XFER
EOM
* Called by code running in aux mem to invoke a
* routine in main memory
XF2MAIN MAC
SEI ; Disable IRQ before XFER
LDX #<]1
STX STRTL
LDX #>]1
STX STRTH
TSX
STX $0101 ; Save alt SP
LDX $0100 ; Load main SP into X
CLC ; Use main mem
CLV ; Use main ZP and LC
JMP XFER
EOM
* Macro called on re-entry to aux memory
* Careful: This enables IRQ - not for use in ISR
ENTAUX MAC
LDX $0101 ; Recover alt SP
TXS
CLI ; Re-enable IRQ after XFER
EOM
* Macro called on re-entry to main memory
* Careful: This enables IRQ - not for use in ISR
ENTMAIN MAC
TXS ; Main SP already in X
LDX ROMIN ; Bank in ROM
LDX ROMIN
CLI ; Re-enable IRQ after XFER
EOM
* Macro called on re-entry to aux memory
* For use in interrupt handlers (no CLI!)
IENTAUX MAC
LDX $0101 ; Recover alt SP
TXS
EOM
* Macro called on re-entry to main memory
* For use in interrupt handlers (no CLI!)
IENTMAIN MAC
TXS ; Main SP already in X
LDX ROMIN ; Bank in ROM
LDX ROMIN
EOM
* Enable writing to main memory (for code running in aux)
WRTMAIN MAC
PHP
SEI ; Keeps IRQ handler easy
STZ WRMAINRAM ; Write to main memory
EOM
* Go back to writing to aux (for code running in aux)
WRTAUX MAC
STZ WRCARDRAM ; Write to aux memory
PLP ; Normal service resumed
EOM
* Enable reading from main memory (for code running in aux LC)
RDMAIN MAC
PHP
SEI ; Keeps IRQ handler easy
STZ RDMAINRAM ; Read from main memory
EOM
* Go back to reading from aux (for code running in aux LC)
RDAUX MAC
STZ RDCARDRAM ; Read from aux memory
PLP ; Normal service resumed
EOM
* Manually enable AltZP + Aux LC (for code running in main)
* Banks ROM out
ALTZP MAC
PHP
SEI ; Disable IRQ when AltZP on
LDA LCBANK1 ; R/W LC bank 1
LDA LCBANK1
STZ SETALTZP ; Alt ZP and LC
EOM
* Manually disable AltZP + Aux LC (for code running in main)
* Banks ROM in
MAINZP MAC
STZ SETSTDZP ; Main ZP and LC
LDA ROMIN ; Bank ROM back in
LDA ROMIN
PLP ; Turn IRQ back on
EOM
* Code is all included from PUT files below ...
* ... order matters!
PUT MAINMEM.LDR
PUT AUXMEM.MOSEQU
PUT AUXMEM.INIT
PUT AUXMEM.VERS
PUT AUXMEM.VDU
PUT AUXMEM.HGR
PUT AUXMEM.SHR
PUT AUXMEM.HOSTFS
PUT AUXMEM.OSCLI
PUT AUXMEM.BYTWRD
PUT AUXMEM.CHARIO
PUT AUXMEM.AUDIO
PUT AUXMEM.MISC
PUT MAINMEM.MENU
PUT MAINMEM.FSEQU
PUT MAINMEM.INIT
PUT MAINMEM.SVC
PUT MAINMEM.HGR
PUT MAINMEM.SHR
PUT MAINMEM.PATH
PUT MAINMEM.WILD
PUT MAINMEM.LISTS
PUT MAINMEM.MISC
PUT MAINMEM.AUDIO
PUT MAINMEM.ENSQ
PUT MAINMEM.ENSQFREQ
PUT MAINMEM.MOCK
PUT MAINMEM.MOCKFREQ
PUT MAINMEM.FONT8
* Automatically save the object file:
SAV APLCORN.SYSTEM
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