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 Bye, Nicolás. ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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