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https://github.com/bobbimanners/Applecorn.git
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140 lines
3.4 KiB
ArmAsm
140 lines
3.4 KiB
ArmAsm
* Load an Acorn BBC Micro ROM in aux memory and
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* Provide an environment where it can run
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* (c) Bobbi 2021 GPLv3
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*
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* Assembled with the Merlin 8 assembler.
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XC ; 65c02
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ORG $2000 ; Load addr of loader in main memory
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* Monitor routines
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BELL EQU $FBDD
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PRBYTE EQU $FDDA
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COUT1 EQU $FDED
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CROUT EQU $FD8E
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AUXMOVE EQU $C311
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XFER EQU $C314
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* Monitor ZP locations
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A1L EQU $3C
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A1H EQU $3D
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A2L EQU $3E
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A2H EQU $3F
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A4L EQU $42
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A4H EQU $43
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* Used by XFER
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STRTL EQU $3ED
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STRTH EQU $3EE
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* Reset vector (2 bytes + 1 byte checksum)
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RSTV EQU $3F2
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* MLI entry point
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MLI EQU $BF00
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* ProDOS MLI command numbers
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QUITCMD EQU $65
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GTIMECMD EQU $82
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CREATCMD EQU $C0
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DESTCMD EQU $C1
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ONLNCMD EQU $C5
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SPFXCMD EQU $C6
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GPFXCMD EQU $C7
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OPENCMD EQU $C8
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READCMD EQU $CA
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WRITECMD EQU $CB
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CLSCMD EQU $CC
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FLSHCMD EQU $CD
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GMARKCMD EQU $CF
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GEOFCMD EQU $D1
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* IO Buffer for reading file (1024 bytes)
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IOBUF0 EQU $4000 ; For loading ROM, OSFILE, *.
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IOBUF1 EQU $4400 ; Four open files for langs
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IOBUF2 EQU $4800
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IOBUF3 EQU $4C00
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IOBUF4 EQU $5000
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* 512 byte buffer sufficient for one disk block
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BLKBUF EQU $5200
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BLKBUFEND EQU $5400
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* Address in aux memory where ROM will be loaded
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AUXADDR EQU $8000
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* Address in aux memory where the MOS shim is located
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AUXMOS1 EQU $2000 ; Temp staging area in Aux
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EAUXMOS1 EQU $3000 ; End of staging area
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AUXMOS EQU $D000 ; Final location in aux LC
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* Macro for calls from main memory to aux memory
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XFAUX MAC
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SEC ; Use aux memory
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BIT $FF58 ; Set V: use alt ZP and LC
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JMP XFER
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EOM
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* Macro for calls from aux memory to main memory
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XFMAIN MAC
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CLC ; Use main memory
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CLV ; Use main ZP and LC
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JMP XFER
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EOM
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* Macro to load addr into STRTL/STRTH
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* Called by code running in main mem
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XFADDR MAC
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PHA
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LDA $C08B ; R/W LC RAM, bank 1
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LDA $C08B
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LDA #<]1
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STA STRTL
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LDA #>]1
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STA STRTH
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PLA
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EOM
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* Macro to backup STRTL/STRTH then load XFADDR
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* Called by code running in aux mem
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XFADDRAUX MAC
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PHA
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LDA STRTL
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STA STRTBCKL
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LDA STRTH
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STA STRTBCKH
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LDA #<]1
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STA STRTL
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LDA #>]1
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STA STRTH
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PLA
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EOM
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* Macro called on re-entry to aux memory
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ENTAUX MAC
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LDX $0101 ; Recover alt SP
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TXS
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PHA
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LDA STRTBCKL
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STA STRTL
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LDA STRTBCKH
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STA STRTH
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PLA
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EOM
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* Macro called on re-entry to main memory
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ENTMAIN MAC
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LDX $0100 ; Recover SP
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TXS
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PHA ; Preserve parm in A
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LDA $C081 ; Bank in ROM
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LDA $C081
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PLA
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EOM
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* Code is all included from PUT files below ...
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PUT LOADER
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PUT MAINMEM
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PUT AUXMEM
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