RE: [stella] VCS.H standardization

Subject: RE: [stella] VCS.H standardization
From: Nicolás Olhaberry <nolh@xxxxxxxxxxxxx>
Date: Mon, 26 Nov 2001 15:10:37 -0300
----- Original Message -----
From: Thomas Jentzsch <tjentzsch@xxxxxx>
To: <stella@xxxxxxxxxxx>
Sent: Monday, November 26, 2001 5:06 AM
Subject: Re: [stella] VCS.H standardization

> (BTW: What is at $285? TIMINT? It is missing in all include files I know
and it's not documented, but DiStella knows it.)

I´ve asked this not so long ago:

 >I always thought that $285 was a timer mirror, look what Dragon fire does:
 >   12DB  2C8502              BIT $0285
 >   12DE  10FB                  BPL $12DB

Here´s what Eckhard Stolberg answered :

 > This is exactly what I tried to describe above. If you start
 > a timer with interrupts enabled ($29E instead of $296 for TIM64T),
 > then bit 7 of address $285 will go high when the timer wraps around
 > from $00 to $FF. Therefore the above loop will wait for the timer
 > to expire without having to change the content of any of the three
 > processor registers by loading from INTIM.

The PIA has other registers too, but they´re not needed for atari games
development, so I don´t think they should be added to stella.h



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