Thanks All,

I really appreciate all the answers.  The code below is what I was looking
for.  I had worked
on this this morning and I had almost the code below but I did not use the
neat trick of setting
up a default subtraction value before testing the input character.  I am
learning slowly but
well,  I think.  I had 2 hex characters (0 to F) for input and I needed the
get the result in the W reg
as a hex number, ex: IN = A1 (ASCII),  output = A1 (HEX).

Works great,  Royce

----- Original Message -----
From: Andrew Warren <aiw@CYPRESS.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, February 04, 2002 7:59 PM
Subject: Re: [PIC]: ASCII to HEX


> Bob Barr <PICLIST@mitvma.mit.edu> wrote:
>
> > The input digits do have to be in the ASCII '0'-'9' range (otherwise
> > doing the '* 10' wouldn't be right.)
> >
> > Royce's original input data is a pair of decimal characters to be
> > converted to hex. The characters 'A' through 'F' just can't be part of
> > valid input data.
>
>     See?  THIS is what happens when you take a perfectly good
> software
>     guy and make him work on everything BUT software for a year and a
>     half.  Sigh...
>
>     Ok, my code and I were both confused.  Here's the routine to
>     translate two ASCII hex digits (0-9 or A-F) into a hex value.  I
>     don't remember Royce saying that his two ASCII digits were
> decimal,
>     so this might be what he wanted:
>
>         LIST R = DEC
>
>         MOVLW   '0'                            HERE IS THE NEAT TRICK, SET
THE CONSTANT
>         BTFSC   CHAR1,6                   TEST
>         MOVLW   'A'-10                     CHANGE THE CONSTANT
>         SUBWF   CHAR1
>
>         MOVLW   '0'
>         BTFSC   CHAR2,6
>         MOVLW   'A'-10
>         SUBWF   CHAR2
>
>         SWAPF   CHAR1,W
>         ADDWF   CHAR2,W
>

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