Re: [stella] Games to be shown in the documentary

Subject: Re: [stella] Games to be shown in the documentary
From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx>
Date: Wed, 7 Jan 1998 09:04:19 -0500 (EST)
> I had thought of this, it seems a good idea. I'm just about a little scared,
> because I'll have to change the code that 'eats' the shields.. any suggestion?
> P.

ok... looking at my code and dredging up memories (*yeech* that code is a 
mess!), I find that the part 
that actually removes the pixel from the shield is after label SH1 in the
code.  Since you're still only removing one pixel from memory at a time,
you don't need to change that part... Currently, the shields are stored
bottom-to-top in the array at $A0 (bottom line of leftmost shield is at
$A0, top line at $A7, bottom line of second shield at $A8, etc).

What I *think* you need to change is, right before the label SH0 (that's
a zero), add an LSR between the AND #$F8 and the following TAX.  That'll
limit the shield-destroying routine to four rows.  Then, you need to
change the draw-shields routine so that the shields start at Shields,
Shields+4, Shields+8 and Shields+12 instead of the current Shields,
Shields+8, Shields+16, and shields+24.  You also need to make that routine
display each line twice, but that's easy - change the LDY #7 to LDY #3,
and do DEY every other line instead of every line.  And you need to change
the shield-initialization code at the end of subroutine BoardInit to only
write four bytes to each shield instead of eight.

That *should* do it and get you 16 bytes of RAM.  Have fun :)



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