10 ;›20 ; *** EQUATES ***›30 ;›40 START =   $4000›50 SIOV  =   $E459›60 INITAD =  $02E2›70 DDEVIC =  $0300   ;START OF DEVICE CONTROL BLOCK (DCB)›80 DUNIT =   DDEVIC+1›90 DCOMND =  DUNIT+1›0100 DSTATS = DCOMND+1›0110 DBUFLO = DSTATS+1›0120 DBUFHI = DBUFLO+1›0130 DTIMLO = DBUFHI+1›0140 DUNUSE = DTIMLO+1›0150 DBYTLO = DUNUSE+1›0160 DAUX1 = DBYTLO+1›0170 DAUX2 = DAUX1+1›0180 ;›0190 ; *** MAIN PROGRAM ***›0200 ;›0210     *=  START›0220     LDA #1      ; CHECK DRIVE #1 FIRST›0230     STA DRVNO›0240 NXTDRV›0250     JSR RDDOT   ;READ THE DRIVE OPTION TABLE›0260     LDA DSTATS  ;CHECK STATUS OF SIO OPERATION›0270     CMP #$01    ;1=OPERATION SUCCESSFUL›0280     BNE NODRV   ;IF NOT SUCCESSFUL, QUIT›0290     LDA #2      ;SET STEP RATE=2, (3 SLOWEST)›0300     STA DOTAB+1›0310     JSR WRTDOT  ;SEND DRIVE OPTION TABLE TO DRIVE›0320     INC DRVNO   ;NEXT DRIVE›0330     JMP NXTDRV›0340 NODRV›0350     RTS         ;EXIT›0360 ;›0370 ; *** SUBS ***›0380 ;›0390 RDDOT ;         READ DRIVE OPTION TABLE›0400     LDA DRVNO›0410     STA DUNIT   ;SET DRIVE #›0420     LDA #$40    ;SET I/O DIRECTION (INPUT)›0430     STA DSTATS›0440     LDA #$4E    ;SET COMMAND TO READ DRIVE OPTION TABLE›0450     STA DCOMND›0460     JSR SIOV    ;EXECUTE›0470     RTS ›0480 WRTDOT ;        WRITE DRIVE OPTION TABLE›0490     LDA DRVNO›0500     STA DUNIT   ;SET DRIVE #›0510     LDA #$80›0520     STA DSTATS  ;SET I/O DIRECTION(OUTPUT)›0530     LDA #$4F›0540     STA DCOMND  ;SET COMMAND TO WRITE DRIVE OPTION TABLE›0550     JSR SIOV    ;EXECUTE›0560     RTS ›0570 ;›0580 ; *** VARIABLES ***›0590 ;›0600 DOTAB›0610     *=  *+$0D   ;DRIVE OPTION TABLE (12 BYTES)›0620 ;›0630 ; *** INITIALIZE DCB ***›0640 ;›0650     *=  DDEVIC  ;DEVICE CONTROL BLOCK (SEE MAPPING THE ATARI)›0660 DCB›0670     .BYTE $31,$01,$4E,$40›0680     .WORD DOTAB›0690     .BYTE $01,$00,$0C,$00›0700     .BYTE $01,$00›0710 ;›0720 ; *** SET TO RUN ON LOAD ***›0730 ;›0740     *=  INITAD›0750     .WORD START›0760     .END ›+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++