Closer look at MOVFP W,FSR0... Looking at the 1995 manual Table 15-2 (PIC 17CXX instruction set) for MOVFP f,p it shows f=0to255 and p=0to31. This is not the 0/1 situation as is for s in clrf f,s. Use of W=0 and F=1 makes sense to me in clrf but not movfp. If f is 0, it would activate indirect addressing using INDF0, right? What do you think is going on with MOVFP W,FSR0 as shown below? --------------------------------------------------------------------- Greetings, I just recently started learning the pic assembly language and have a question regarding the use of W which is defined in P17CXX.INC as shown below: W EQU H'0000' F EQU H'0001' <=== I understand F but not W. See movfp below... Here is a code segment from App Note 547 example 5 (serint.asm): start clrf FSR1,F ;assign FSR1 as S.P. (What is S.P.?, stack?) decf FSR1,F ; / movlw 0x20 movfp W,FSR0 There is also a line of code in serint.asm as follows: clrf WREG,F ;clr W How can W and WREG be the same if WREG is addr 0Ah and W is defined as 0? I've read the section on indirect addressing and I thought I understood it. I've used this type of feature many times with other architectures but this W stuff has me puzzled. Please help. Thanks. -Brian Leger- bleger@harris.com