Re: Star Trek spinner jumps

> Nothing wastes time like assumptions.
>
> In case this is news to anyone else, the Sega "single player contoller
> board" does NOT send Clock and Direction signals for the spinner to the
CPU.
>
> The interface board has a 8 bit counter chip on it, and sends 1 bit for
> direction and 7 bits indicating a pulse count.

Oops. I thought you knew this?

> So, if one of those bits is bad, you'll get bizare jumps all over the
> place, because you wont get a true count of the number of pulses since the
> last poll of the board.

Right, so like if the 'n' bit is bad, you'll get like a sudden jump of like
2 to the n-1. Or something like that.

> This thing needs a "Theory of operation" sheet -- it's too simple a board
to
> spend this much time tracing down what the damn thing does.

That's why it's usually a connection :-)

> Did all the Sega games -- raster and Vector -- use this same interface
> method ? Is it possibly documented someplace else ?

Yes. No.

> (Oh, yeah it works now. Of course, I tested all the lines and they were
> fine, and it's working with the cover of the card cage hanging upside
down.
> I'll see what happens when I put it back on. :-)

Yep, that's a Sega XY game for ya!

--
Mark Jenison
Has all his Sega XY games upside down so they work
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