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Groups > comp.sys.apple2.programmer > #5068

Re: Assembly 80 column text

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On Tuesday, April 9, 2019 at 7:23:08 PM UTC-6, Du Hast wrote:
> On Tuesday, April 9, 2019 at 9:19:51 AM UTC-4, Antoine Vignau wrote:
> > The three above messages are great.
> > Note that you wrote $A0 (zero page addressing) instead of #$A0 (direct space char value) in the ENTRY routine
> > 
> > av
> 
> They were great, and it's helped me out a lot in that things are working better now.  
> 
> So much of my confusion is interpreting the documentation.  TABV is never mentioned anywhere I could find.  Some docs were practically saying that CH and OURCH were interchangeable, which is doesn't seem like they are.  And I'm confused on some of the monitor routines.
> 
> Like clear line, CLEOLZ.  There's F.CLEOLZ, B.CLEOLZ, X.GSEOLZ.  What's Where just says they all clear the line, but obviously there must be a difference?


Sometimes the labels define the same address point depending on who labeled the source code.  But more often than not, multiple variations of the same label usually mean an alternate entry point for machine language programmers.

Take $F948, $F94A and $F94C, for instance.  All print a row of characters to the screen and basically call the same code, but with different entry points.

So, your code above can be reduced from:

         STA   CHAR       ; SAVE CHAR
CLEAR    LDY   #$4F       ; 80 CHARS
         LDA   CHAR       ; GET CHAR
LOOP     JSR   COUT       ; PRINT IT
         DEY              ; COUNT-1
         BNE   LOOP       ; NOT ZERO

to:

         LDX #$4F
         JSR $F94C

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Assembly 80 column text Du Hast <duhast6377@gmail.com> - 2019-04-08 18:23 -0700
  Assembly 80 column text gids.rs@sasktel.net - 2019-04-08 18:57 -0700
    Assembly 80 column text gids.rs@sasktel.net - 2019-04-08 18:59 -0700
      Assembly 80 column text gids.rs@sasktel.net - 2019-04-08 19:06 -0700
        Assembly 80 column text Antoine Vignau <antoine.vignau@laposte.net> - 2019-04-09 06:19 -0700
          Re: Assembly 80 column text Du Hast <duhast6377@gmail.com> - 2019-04-09 18:23 -0700
            Re: Assembly 80 column text gids.rs@sasktel.net - 2019-04-09 19:51 -0700
              Re: Assembly 80 column text Du Hast <duhast6377@gmail.com> - 2019-04-10 17:25 -0700
                Re: Assembly 80 column text D Finnigan <dog_cow@macgui.com> - 2019-04-11 00:50 +0000
                Re: Assembly 80 column text Michael J. Mahon <mjmahon@aol.com> - 2019-04-10 20:40 -0500
                Re: Assembly 80 column text Du Hast <duhast6377@gmail.com> - 2019-04-11 19:18 -0700
                Re: Assembly 80 column text Antoine Vignau <antoine.vignau@laposte.net> - 2019-04-11 21:26 -0700
                Re: Assembly 80 column text Michael J. Mahon <mjmahon@aol.com> - 2019-04-12 00:43 -0500
                Re: Assembly 80 column text Antoine Vignau <antoine.vignau@laposte.net> - 2019-04-12 09:59 -0700
                Re: Assembly 80 column text Michael Pohoreski <michael.pohoreski@gmail.com> - 2019-04-12 13:17 -0700
                Re: Assembly 80 column text Antoine Vignau <antoine.vignau@laposte.net> - 2019-04-12 14:20 -0700
                Re: Assembly 80 column text Michael Pohoreski <michael.pohoreski@gmail.com> - 2019-04-12 15:21 -0700
                Re: Assembly 80 column text Michael J. Mahon <mjmahon@aol.com> - 2019-04-12 17:18 -0500
                Re: Assembly 80 column text Du Hast <duhast6377@gmail.com> - 2019-04-12 15:15 -0700
                Re: Assembly 80 column text Michael J. Mahon <mjmahon@aol.com> - 2019-04-12 17:25 -0500
                Re: Assembly 80 column text gids.rs@sasktel.net - 2019-04-12 19:08 -0700
                Re: Assembly 80 column text gids.rs@sasktel.net - 2019-04-10 21:52 -0700
                Re: Assembly 80 column text James Davis <JPD.Enterprises@outlook.com> - 2019-04-11 19:19 -0700

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