Well I finally put together another ROM carrier so I could play it on a real
Atari. Cool. Comes up great on my traditional 4-button model, but when I
try it on my Rainbow model, you know, the miniature, modern looking one with
the rainbow silkscreen, I have problems. More often than not, when I power
it up I get a blank screen, or some perversion of the game. Only on
occasion, maybe 1 in 5 tries do I get the game you had intended.
Although there may be others, I know of one other game that behaves
differently on the *Rainbow* than it does on the *traditional*. Yar's
Revenge. On the *traditional* when you power it up you get a nice black
background. On the *rainbow*, sometimes you get the correct appearance, but
sometimes you get stripes down either the left or the right side of the
screen. Usually they're green.
While working on z26, I made an interesting discovery relating to this.
Paul Robson's original A26 on which z26 is based, initializes the contents
of the emulated RAM and TIA registers to zero. A reasonable thing to do.
But I can be positively mediaeval at times. I thought I saw a way to save a
few bytes of code in the .COM file by leaving these things uninitialized.
After all, who in their right mind would depend on the contents of hardware
after a power up? Well, you might be surprised. In any event, when I left
these things uninitialized, Yar's Revenge displayed a nice green stripe
right down the left side of the screen when the emulator was started.
So I guess the moral of the story is that the *rainbow* Atari 2600 seems to
power up with TIA registers and/or RAM in a different state than the
*traditional* model. Not that this has anything to do with Multi050... but
who knows ???
BTW, I still haven't fixed object wrapping in z26, but I really like how
obvious Multi050 makes the bug. I know of no other game that makes it so
obvious what needs to be done. Cool.
John Saeger
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