[stella] Playfield Byte Mapping Patterns?

Subject: [stella] Playfield Byte Mapping Patterns?
From: "Mark Graybill" <saundby@xxxxxxxxxxxx>
Date: Sat, 28 Sep 2002 18:01:42 -0700
Hello, all. This is my first post to the list.

Something I appear to be seeing that isn't reflected in the Stella
Programmer's Guide as far as I can tell is that PF2 appears to get mapped
left to right from bit 0 to bit 7, as opposed to from bit 7 to bit 0 as is
the case with PF1. This is with the playfield reflection bit in CTRLPF
cleared so the PF bytes are mapped as PF0-PF1-PF2-PF0-PF1-PF2. I saw this
behavior both with the StellaX emulator and my 7800 with an EPROM loaded
with my code.

I didn't see anything that seems to control whether it gets mapped from
lowest bit to highest or highest bit to lowest.

So, my questions are:

Is this the expected behavior?
Is there a way of making PF2 map the other way around, or do I need just
work with it as-is and mirror the bit pattern?



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