SUBDEL
         PLA
         TAY
         PLA
         TAX
         PLA
         STA   :SCNT
         PLA
         STA   :SINDEX
         PLA
         STA   ADDR1
         PLA
         STA   ADDR1+1
         TXA
         PHA
         TYA
         PHA
         LDY   #0
         STY   :SCERR
         LDA   (ADDR1),Y
         STA   :S1LEN     
         LDA   :SCNT
         BEQ   :OKEXIT

         LDA   :SINDEX
         BEQ   :ERREXIT   
         LDA   :S1LEN
         CMP   :SINDEX
         BCC   :ERREXIT
         LDA   :SINDEX
         CLC
         ADC   :SCNT
         BCS   :TRUNC     ;TRUNCATE IF INDEX

         STA   :SIDX      

         TAX   
         DEX
         CPX   :S1LEN
         BCC   :CNTOK     


         BEQ   :TRUNC     

         LDA   #$0FF
         STA   :SCERR     

:TRUNC
         LDX   :SINDEX    

         DEX
         STX   :S1LEN
         LDA   :SCERR
         BEQ   :OKEXIT
         BNE   :ERREXIT
:CNTOK
         LDA   :S1LEN     
         SEC
         SBC   :SIDX      
         TAX
         INX
         BEQ   :OKEXIT    
                          ; CHAR
:MVLP
         LDY   :SIDX
         LDA   (ADDR1),Y  
         LDY   :SINDEX
         STA   (ADDR1),Y  ;MOVE IT DOWN
         INC   :SINDEX
         INC   :SIDX      
         DEX
         BNE   :MVLP      
         LDX   :SINDEX
         DEX   

         STX   :S1LEN
:OKEXIT
         CLC
         BCC   :EXIT
:ERREXIT
         SEC
:EXIT
         LDA   :S1LEN
         LDY   #0
         STA   (ADDR1),Y  
         RTS
:S1LEN   DS    1
:SCNT    DS    1
:SINDEX  DS    1
:SIDX    DS    1
:SCERR   DS    1