[vcf-midatlantic] Woohoo!

Bob Applegate bob at corshamtech.com
Sun Jul 30 08:25:50 EDT 2017

> On Jul 30, 2017, at 4:52 AM, Evan Koblentz via vcf-midatlantic <vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> This popped into my mind: what if you want to display a large amount of text? I assume there's some better way than loading each individual character. The book I'm reading may explain it in a later chapter, and maybe it's counterproductive for me to ask at this point! Not looking for a code example right now. But someone please assure me assembly isn't always * this tedious *.

There are lots of common routines to do this. A good collection of handy 6502 routines is here:

http://www.6502.org/source/ <http://www.6502.org/source/>

There’s an entry for PRIMM, and if follow that page to the last version (by Russ Archer) you’ll see a very nice way of doing it.  Just change to your local character-output subroutine.

    jsr     PUTSTRI
    db      “Hello world.  Wow.”
    db      0

Let’s not get into religious discussions about whether strings should be in-line with the code or not.  This was just an example.

Suggestions on your original code:

Use labels, not hard coded addresses (“magic numbers”).  Most assemblers also allow character constants, like:

        lda     #’H’
    jsr     OUTCH

Etc.  Use of magic numbers is highly discouraged and would fail pretty much any code review.  

But… congrats on your first 6502 assembly language program!


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