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Line No. Rev Author Line
1 22 dilbert57 
*
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** FLEX 9 DISK DRIVERS
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*
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* FOR SYS09BUG ON THE DIGILENT SPARTAN 3 STARTER BOARD
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* WITH I/O MAPPED AT $XE000
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* AND ROM MAPPED AT $XF000
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* THE DIGILENT SPARTAN 3 STARTER BOARD HAS 1MBYTE OF SRAM
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* THE FIRST 64K IS USED BY FLEX,
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* THE SECOND 192K IS USED AS A ROM DISK
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* THE REMAINING RAM IS USED FOR A RAM DISK
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*
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* These drivers should also work on the B5-X300 board
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* although there is only enough room for the ROM Disk.
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*
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IMASK  EQU $10     IRQ MASK CC
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FMASK  EQU $40     FIRQ MASK CC
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TRPAGE EQU $0E     PAGE $E000 DAT ADDRESS
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DATREG EQU $FFF0   DAT REGISTERS
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       ORG   $DE00
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*
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* DISK DRIVER JUMP TABLE LAST UPDATE: 22/12/2006
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* Disk driver for RAM Disk.
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*
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* 14 SECTORS PER TRACK
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* 16 * N TRACKS PER DISK
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*
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* ROM DISK OCCUPIES $10000 - $1E000, $20000 - $2E000, $30000 - $3E000
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* RAM DISK OCCUPIES $40000 - $4E000 ... $F0000 - $FE000
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* Track Buffer page mapped at $E000 - $EFFF
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* TRPAGE = $0E = 14 x $1000 (4 K pages)
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* LEAST SIGNIFICANT NYBBLE OF THE DAT IS INVERTED
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* ON SWTPC ROM AT $XF000 AND IO AT $XE000
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* APPEARS THROUGHOUT THE MEMORY SO MUST BE SKIPPED OVER
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* WHEN USING RAM AS A RAMDISK.
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* THE MSN OF THE TRACK MAPS INTO THE MSN OF THE DAT
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* THE LSN OF THE TRACK NUMBER INDEXES INTO THE 4K RAM PAGE
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* THE SECTOR MAPS INTO THE LSN OF THE DAT WHICH IS INVERTED
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*
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*
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READ   JMP   READSC
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WRITE  JMP   WRITSC
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VERIFY JMP   BUSY
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RESTOR JMP   RESTR1
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DRIVE  JMP   DRVSEL
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DRVRDY JMP   CHKDRV
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QUICK  JMP   CHKDRV
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COLDDR JMP   INITDR
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WARMDR JMP   WARMD1
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SEEK   JMP   SEEKTS
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*
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* RAM SPACE
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*
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WRKDR  FDB   0
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WRKTR  FDB   0,0,0,0
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SECPTR FDB   0
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TRKCNT FCB   0
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SECCNT FCB   0
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VERERR FCB   0
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CCSAVE FCB   0
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*
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DRVBAS FCB   $10  DRIVE 0
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       FCB   $40  DRIVE 1
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       FCB   $40  DRIVE 2
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       FCB   $40  DRIVE 3
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*
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INITDR RTS
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WARMD1 RTS
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*
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* Seek track and sector
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* A holds track number (0-32)
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* B holds sector number (1-14)
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*
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SEEKTS STA  TRKCNT
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       STB  SECCNT
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       ANDCC  #$FE   ; CLEAR CARRY
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       ORCC   #$40   ; SET Z
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       RTS
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*
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* MAP RAM DISK INTO I/O SPACE
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*
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MAPIN  TFR   CC,A     ; Save state of interrupt masks
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       STA   CCSAVE
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       ORCC  #FMASK+IMASK ; Mask interrupts while IO mapped out
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       LDA   TRKCNT
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       LDU   #DRVBAS  ; Point to Drive base offset
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       LDB   WRKDR    ; Get working drive number
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       ADDA  B,U      ; Add Base offset into RAM
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       ANDA  #$F0     ; Mask MSN
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       STA   ,-S      ; Save A on stack
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*
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       LDA   SECCNT
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       SUBA  #1       ; Sectors 1 to 14 => 0 to 13
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       EORA  #$0F     ; Complement LSNybble
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       ANDA  #$0F
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*
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       ADDA  ,S+       ; Add sector to LSN of Track and pop
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       STA   DATREG+TRPAGE
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*
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       LDA   TRKCNT   ; LSN of Track indexes into 4K page
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       ANDA  #$0F
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       ADDA  #TRPAGE*16
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       STA   SECPTR
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       CLR   SECPTR+1
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       LDU   SECPTR
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       RTS
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*
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* MAP RAM DISK OUT OF MEMORY
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*
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MAPOUT LDA   #TRPAGE  ; Point to the I/O page
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       EORA  #$0F     ; Complement LSNybble
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       STA   DATREG+TRPAGE ; map in I/O page
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       LDA   CCSAVE   ; restore interrupt masks
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       TFR   A,CC
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       RTS
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*
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* READ DISK DRIVER
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*
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READSC LBSR  SEEKTS   ; SEEK TRACK & SECTOR
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       PSHS  U,X
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       BSR   MAPIN    ; MAP RAM DISK INTO I/O SPACE
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*
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       CLRB
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READ3  LDA  ,U+
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       STA  ,X+       ; Move Sector to FCB
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       INCB
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       BNE   READ3
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*
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       BSR  MAPOUT    ; MAP RAM DISK OUT OF I/O SPACE
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       CLRB           ; Z SET C CLEAR
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       PULS U,X,PC    ; Restore registers and return
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*
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* WRITE DISK DRIVER
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*
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WRITSC BSR   SEEKTS   ; SEEK TRACK & SECTOR
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       PSHS  U,X
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       BSR   MAPIN    ; MAP RAM DISK INTO I/O SPACE
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*
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       CLRB
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WRIT3  LDA   ,X+      ; COPY FCB BLOCK TO RAM DISK
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       STA   ,U+
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       INCB
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       BNE    WRIT3
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*
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       BSR    MAPOUT  ; MAP OUT RAM DISK
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       CLRB           ; SET Z, CLEAR C
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       PULS   U,X,PC  ; Restore registers and return
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*
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* RESTORE DISK DRIVER (SEEK TRACK 00)
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*
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RESTR1 PSHS A
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       CLRA           ; Track 0
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       LDAB  #$01     ; Sector 1
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       LBSR  SEEKTS
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       PULS  A,PC
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*
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* CHECK FOR BUSY
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* Doubles as VERIFY
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*
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BUSY   CLRB            Never busy
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       RTS
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*
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* DRIVE SELECT DISK DRIVER
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*
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DRVSEL PSHS  X
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       LDA   3,X       GET DRIVE # FROM FCB
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       CMPA  #3
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       BLS   DRVS2     IF > 3, SET IT TO 0
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       CLRA
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DRVS2  BSR   MXWT      MOVE X TO WORKING TRK
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       LDB   TRKCNT
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       STB   0,X       SAVE TRACK
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       STA   WRKDR     SAVE DESIRED DRV AS WORKING DRV
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       BSR   MXWT      MOVE X TO WORKING TRK
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       LDA   0,X       GET WORKING TRK ON DESIRED DRV
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       STA   TRKCNT    UPDATE 1771 TRACK REG
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       CLRB            ; SET Z, CLEAR C
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       PULS   X,PC
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*
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* MOVE INDEX REG TO POINT TO
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* WORKING TRACK STORAGE
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*
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MXWT   LDX   #WRKTR    POINT TO START OF STG
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       LDB   WRKDR     GET WORKING DRIVE
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       ABX
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MXWT2  RTS
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*
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* CHECK DRIVE READY DISK DRIVER
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*
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CHKDRV LDA   3,X
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       CLRB             ; CLEAR C, SET Z
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       RTS
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 END

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