Re: [stella] Help Interpreting Code

Subject: Re: [stella] Help Interpreting Code
From: "Roger Williams" <mer02@xxxxxxxxxxxxx>
Date: Sat, 13 Jul 2002 21:01:36 -0700
From: Roagie <roagie@xxxxxxx>

> Here's another quick question while I'm at it. Is there an adavantage to
> using hex, for example, when defining player graphics? It seems to be much
> easier to use the binary notation. i.e. $20 = %00100000
> You can design your sprite right in the code in this manner! There has to
> a downside, what is it?

Only that it requires more typing.  $20 and %00100000 are treated
exactly the same by the assembler.

Often if you see $hex graphics it's because they came from a disassembly,
or were generated by a "helper" program which the programmer used
to draw graphics outside the assembler.  You should also be aware that
graphics often end up upside-down in memory, because some operations
work better with DEC toward zero than INC (which doesn't even exist
for the accumulator) toward an arbitrary comparison point.

Oh, and when you get to playfield graphics, the middle playfield
register is also reversed left-to-right.  Just to keep you on your toes :-)

--Roger Williams

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