RE: [stella] 7800 programs -- potential problems?

Subject: RE: [stella] 7800 programs -- potential problems?
From: Eckhard Stolberg <Eckhard_Stolberg@xxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 24 Jan 2000 18:25:31 +0100
>Not to mention you only get two writes to the control register! After 2
>writes, it halts the processor!!  There are two chained flipflops that
>shift a "1" through each bit, and on the third write to the control register,
>the last output goes high, which runs thru a transistor to the processor's
>HALT line, stopping the processor.

Are you sure about this? I think Dan Boris once mentioned to me that
the processor would only be HALTed after two consecutive writes to the
state control register. My replacement BIOS for the 7800 switches
back and forth between BIOS and game ROM several times and doesn't lock
up. Also Atari's OS has a loop at the very beginning that clears several
registers, including some below $20, which would also write to the state
control register. This would happen through a different address every time,
though.


Thanks, Eckhard Stolberg



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