dnm.src

;08/22/84 ds
;********************************
;**  change device number util.**
;**  & sector increment util.  **
;********************************
;
chgdnm           
        ldx  cmdsiz     ; check for drive number after command
        dex      
        beq  chgtgl     ; if none then toggle what you have
        lda  cmdbuf+1    
        tay     ; save
        cmp  #'R        ; is it "r" if so then goto cmd section
        beq  cmdsec      
        cmp  #'S        ; is it "s" if so then goto cmd section
        beq  cmdsec      
        cmp  #'9        ; is it "9"
        beq  donine      
        cmp  #'8        ; * * * "8"
        bne  chgerr      
doeght           
        ldx  #$08        
        bne  donchg      
chgtgl  lda  tedrv      ; toggle what you have
        cmp  #$08        
        beq  donine      
        bne  doeght      
chgerr           
        lda  #badcmd    ; invalid drive number or syntax
        jmp  cmderr      
donine           
        ldx  #$09        
donchg           
        stx  tedrv       
        txa      
adjdrv  asl  a   
        asl  a          ; shft into bit 2
        and  #%00000100          
        eor  #%00000100         ; $fef0 = 1, $fec0 = 0
        sta  tdstat      
        lda  portc       
        and  #%11111011         ; clear bit 2
        ora  tdstat     ; or in dev#
        sta  portc       
        rts      
;
cmdsec  dex      
        beq  chgerr     ; br, error
        ldx  #$01       ; just in case
        lda  cmdbuf+2   ; retrieve
        cpy  #'R        ; br, retry w/ x=1
        beq  rtyok       
        dex     ; x=0
rtyok   sta  secinc,x   ; change sector interleave or retry
        rts      
;       .end