mirror of
https://github.com/dschmenk/apple2pi.git
synced 2024-11-24 12:31:30 +00:00
243 lines
3.2 KiB
ArmAsm
Executable File
243 lines
3.2 KiB
ArmAsm
Executable File
;****************************************
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;*
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;* OPTION ROM SPACE @ $C800
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;*
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;****************************************
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;*
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;* RETURN SLOT*16 IN X REG, SLOT IN Y REG
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;*
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GETSLOT:
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TSX
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LDA $102,X ; GET MSB OF RETURN ADDRESS
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STA IOSLOT
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AND #$0F
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TAY
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LDA SLOT16
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STA SAVE16,Y ; SAVE SLOT16 LOCATION
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TYA
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ASL
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ASL
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ASL
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ASL
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STA SLOT16
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TAX
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RTS
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;*
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;* OUTPUT BYTE TO ACIA
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;*
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SENDACC:
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PHA
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LDA SLOT16
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ORA #$89+1 ; ACIASR
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TAX
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SENDWT: LDA $C000-1,X
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AND #$10
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BEQ SENDWT
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DEX ; ACIADR
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PLA
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STA $C000-1,X ; AVOID PHANTOM READ OF DATA REG
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RTS
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;*
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;* INPUT BYTE FROM ACIA
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;*
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RECVACC:
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LDX SLOT16
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RECVWT: LDA ACIASR,X
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AND #$08
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BEQ RECVWT
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LDA ACIADR,X
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RTS
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;*
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;* WAIT FOR DELAY
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;*
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WAIT: SEC
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WAIT2: PHA
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WAIT3: SBC #$01
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BNE WAIT3
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PLA
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SBC #$01
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BNE WAIT2
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RTS
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;*
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;* SYNC WITH HOST
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;*
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SYNC: LDA INDCTR
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PHA
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LDA #$0B
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STA ACIASR,X ; RESET STATUS REGISTER
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STA ACIACR,X ; SET CONTROL REGISTER
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LDA #$10
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STA ACIAMR,X ; SET COMMAND REGISTER (115K BAUD)
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LDA #$80
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JSR WAIT
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STA STROBE ; CLEAR KEYBOARD STROBE
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SYNCLP: LDA #SYNC_REQ
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JSR SENDACC
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INY
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TYA
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AND #$07
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TAY
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LDA SPIN,Y
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STA INDCTR
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LDA #$FF
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JSR WAIT
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LDA KEYBD
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BPL CHKRSP
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STA STROBE
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PLA
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.IFNDEF DEBUG
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STA INDCTR
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.ENDIF
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NODEV: LDA #PDNODEV
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RTS
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SPIN: DB $A1, $AF, $AD, $DC, $A1, $AF, $AD, $DC
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CHKRSP: LDX SLOT16
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LDA ACIASR,X
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AND #$08
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BEQ SYNCLP
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LDA ACIADR,X
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CMP #SYNC_ACK
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BNE SYNCLP
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LDA IOSLOT
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AND #$0F
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TAY
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LDA #SYNC_ACK
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STA SYNCED,Y
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PLA
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.IFNDEF DEBUG
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STA INDCTR
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.ENDIF
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LDA #$00
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RTS
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RESYNC: JSR SYNC
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BEQ DOCMD
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RTS
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;*
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;* DO STATUS, READ, WRITE COMMAND
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;*
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DOCMD: LDA ACIACR,X ; CHECK FOR ANY REASON TO RESYNC
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CMP #$0B
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BNE RESYNC
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LDA ACIAMR,X
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CMP #$10
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BNE RESYNC
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LDA SYNCED,Y
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CMP #SYNC_ACK
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BNE RESYNC
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LDA PDUNIT ; FORMAT COMMAND FOR SIDRIVE AND SEND IT
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ASL
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LDA PDCMD
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ROL
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ASL
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ORA #$A0
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JSR SENDACC
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CLC
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ADC #$01
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STA CMDACK,Y
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LDA PDBLKL
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JSR SENDACC
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LDA PDBLKH
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JSR SENDACC
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CHKACK: JSR RECVACC ; WAIT FOR CORRECT ACK (MAY BE OUTSTANDING A2PI REQUESTS)
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CMP CMDACK,Y
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BNE CHKACK
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;*
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;* BRANCH TO COMMAND HANDLER
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;*
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LDA PDCMD
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AND #$03
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TAY ; CPY #PDSTATUS
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BEQ STATUS
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DEY ; CPY #PDREAD
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BEQ RDBLK
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DEY ; CPY #PDWRITE
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BEQ WRBLK
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.IFDEF DEBUG
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LDA #'?'
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STA INDCTR+6
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.ENDIF
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IOERR: LDA #PDIOERR
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RTS
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;*
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;* SIDRIVE STATUS - RETURN NUMBER OF BLOCKS OR NODEV
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;*
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STATUS:
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.IFDEF DEBUG
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LDA #'S'-$40
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STA INDCTR+3
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.ENDIF
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LDA IOSLOT
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AND #$0F
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TAY
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JSR RECVACC
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STA SCRTCH6,Y
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JSR RECVACC
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STA SCRTCH7,Y
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JSR RECVACC
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PHA
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LDX SCRTCH6,Y
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LDA SCRTCH7,Y
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TAY
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PLA
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RTS
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;*
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;* READ A BLOCK (512 BYTES) FROM SIDRIVE
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;*
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RDBLK:
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.IFDEF DEBUG
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LDA #'R'-$40 ; LDY #$00
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STA INDCTR+4
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.ENDIF
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RDBLKL: JSR RECVACC
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STA (PDBUFF),Y
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INY
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BNE RDBLKL
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INC PDBUFH
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RDBLKH: JSR RECVACC
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STA (PDBUFF),Y
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INY
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BNE RDBLKH
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JMP RECVACC
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;*
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;* WRITE A BLOCK (512 BYTES) TO SIDRIVE
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;*
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WRBLK:
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.IFDEF DEBUG
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LDA #'W'-$40 ; LDY #$00
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STA INDCTR+5
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.ENDIF
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WRBLKL: LDA (PDBUFF),Y
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JSR SENDACC
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INY
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BNE WRBLKL
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INC PDBUFH
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WRBLKH: LDA (PDBUFF),Y
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JSR SENDACC
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INY
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BNE WRBLKH
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JMP RECVACC
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.IFDEF ALTBOOT
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;*
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;* PRINT THE BOOT MESSAGE AT THE TOP OF THE SCREEN
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;*
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PUTMSG: LDY #$00
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PUTC: LDA MSG,Y
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BMI FILLEOL
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ORA #$80
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STA MSGLN,Y
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INY
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BNE PUTC
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MSG: DB "PRESS 'M' FOR BOOT MENU", $A0
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;*
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;* CLEAR THE MESSAGE AT THE TOP OF THE SCREEN
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;*
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CLRMSG: LDY #$00
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LDA #$A0
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FILLEOL:
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STA MSGLN,Y
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INY
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CPY #40
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BNE FILLEOL
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RTS
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.ENDIF
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