[vcf-midatlantic] Woohoo!

[Evan Koblentz]

Made my first assembly program just now. :)

http://snarc.net/h.jpg

I was nudged by Ragooman, inspired by attending Kfest, and grateful for 
the book "Apple Roots" (the previously recommended book "Assembly Lines" 
left my brain in a knot after 5 pages). I read chapters 1, 3, and 4 -- 
skipped chapter 2 about number systems because I already understand that 
well enough to fake it and it didn't seem pivotal to * jumping in and 
doing something *.

I used ProDOS Assembly Tools which I downloaded from the Asimov site. 
(Adam convinced me to switch to a real program like Merlin soon.) Tried 
the sample program (ADDNRS) in chapters 3/4 and got it to work after 
Facebook user Katherine S. in the Apple II group noted that I was 
missing some spaces in the sample code. After that it assembled without 
errors. Our own list member Paul H. provided additional insight.

Then, armed with sleep-deprived confidence, I went back and applied what 
I learned to the "HI" example in chapter 1. That worked too, so I looked 
up the number chart at the back of the book and changed it to HELLO 
WORLD. It worked but I had a typo in the output: it showed a hyphen 
instead of a space. That was a good thing because it forced me to 
download the manual and learn how to load and edit the listing. 
Corrected it and this time it showed HELLO WORL ... what happened to the 
D? Looked again and I'd forgotten the final $FDED to display what I 
LDA'd. Okay then! Now it works.

I have absolutely no clue if this is the "correct" way to make a hello 
world in Apple II 6502 assembly. I understand there's probably a more 
efficient way to do it. But for now, I basically skimmed three of the 
first four chapters and wound up with this:

1 ORG $1000
2  LDA #200
3  JSR $FDED
4  LDA #197
5  JSR $FDED
6  LDA #204
7  JSR $FDED
8  LDA #204
9  JSR $FDED
10  LDA #207
11  JSR $FDED
12  LDA #160
13  JSR $FDED
14  LDA #215
15  JSR $FDED
16  LDA #207
17  JSR $FDED
18  LDA #210
19  JSR $FDED
20  LDA #204
21  JSR $FDED
22  LDA #196
23  JSR $FDED
24  RTS

Efficient or not, it works!

________________________________
Evan Koblentz, director
Vintage Computer Federation
a 501(c)(3) educational non-profit

evan at vcfed.org
(646) 546-9999

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