[stella] I'm a mountain man and I'm okay...

Subject: [stella] I'm a mountain man and I'm okay...
From: crackers@xxxxxxxx
Date: Wed, 17 Sep 1997 19:41:55 -0400 (EDT)
Well, I've been working a little bit on my virtual pet game today. Most of it
on paper (drawing sprites, flowcharts, etc) but I did do the background
graphics for the game.

I now know why all those activision games use mountains and a sunset...
it looks cool, and it's easy to do.

Infact, from this experience I now have another insight into why something
odd about the 2600 turns out not to be so odd after all.

Have you ever wondered why PF0 reads from bits 4 to 7, PF1 from 7 to0,
and PF0 from 0 to 7?

Well, if you reflect the playfield, any value you stick into all three
PF locations makes a nice symetrical playfield. It never dawned on me before
that that would be why it was done. If you don't want a symetrical
playfield it can be a pain in the ascii, but if you do then only one byte
is needed for all the PF registers. Neat huh? I'm sure all the more
experienced programmers were already aware of this, but it was a 
"great enlightening" to me. Yes, suddenly something about the 2600 makes
sense. It's really cool when you have one of these experiences.

I have a question now for the more experienced programmers...

One could really easily create a symetrical horizontally scrolling playfield
by using ROL and ROR the only problem is the Carry Bit. How can I easily
remove the problem of the Carry Bit and just have Bit 7 rotate into
bit 0 and vice versa?

                       (Tickled pink from hell!!!!)


Accordionist - Wethifl Musician - Atari 2600 Collector | /\/\
*NEW CrAB URL* http://www.hwcn.org/~ad329/crab.html ***| \^^/
Bira Bira Devotee - FES Member - Samurai Pizza Cats Fan| =\/=

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