Hi,

I am constantly updating R0 and R1. I wish to do CJNE but can't. What am I doing wrong? I looked at "Bible" and see I can't do this, but how can it be done?

here is the code

; GET DIFFERNCE BETWEEN OLD AND NOW
GETDIFFERENCE:  MOV A,R1               ;R1 IS OLD 
                CJNE A, R0, CheckLess  ;SEE IF SAME ERROR IS HERE
                JMP MAIN               ;OLD & NEW ARE SAME
CheckLess:        JC OldLessThanNow    ;R0 is less than R1
OldGreaterThanNow: MOV A,R1
                   SUBB A, R0
                   MOV R5,A          ;R5 = # OF TIMES TO RUN LOOP
                   MOV A,R0          ;R0 = NOW 
                   MOV R1,A          ;R1 = OLD 

                 ;NOW SET DI BIT AND RUN LOOP FOR A# OF TIMES
                   SETB DI
                   DJNZ R5,LOOP
                   JMP MAIN

OldLessThanNow:    MOV A,R0
                   SUBB A, R1
                   MOV R5,A ;        R5 = # OF TIMES TO RUN LOOP
                   MOV A,R0 ;R0 = NOW
                   MOV R1,A ;R1 = OLD

                  ;NOW SET DI BIT AND GO TO LOOP FOR A# OF TIMES
                   CLR DI
                   DJNZ R5,LOOP
                   JMP MAIN

Thank You,
Steve