Subject: RE: [stella] the B. Watson's problem... From: Nicolás Olhaberry <nolh@xxxxxxxxxxxxx> Date: Mon, 23 Aug 1993 20:33:27 -0300 |
----- Original Message ----- From: Eckhard Stolberg <Eckhard_Stolberg@xxxxxx> To: <stella@xxxxxxxxxxx> Sent: Tuesday, August 21, 2001 3:50 PM Subject: Re: [stella] the B. Watson's problem... > For TIM64T and TIM1T it should be the same as INTIM. For TIM8T and > TIM1024T you would be reading the 'timer overflow register'. I'm > not quite sure what it does, but I think it counts how ofter the > timer has gone from $00 to $FF. I see. Has anybody posted on this list all the 6532 PIA registers and their addresses? > $29D and $29E are TIM8T and TIM64T with interrupt enabled. The > 6507 processor in the VCS can't handle interrupts, so this isn't > really much different from the normal timer registers. However, > since the RIOT keeps the interrupt flag in an extra register > $285, I think), you might be able to do a wait for timer loop > with a BIT instruction, since the timer interrupt flag is at D7. Mmm... Could you explain that again? I don´t think that I understood it. I always thought that $285 was a timer mirror, look what Dragon fire does: 12DB 2C8502 BIT $0285 12DE 10FB BPL $12DB > BTW, where did you find these addresses? Are you currently > working on a disassembly of a VCS game? No, I had been working on a VCS emulator for some time, so I had seen a lot of strange memory accesses ;-) $2A2 is accessed by Marine wars, $29D and $29E by Starfox, but I´ve never took the time to disassemble them. I can´t get a stable screen with those games, so I probably will... 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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