Subject: Re: Re: [stella] the B. Watson's problem... From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx> Date: Wed, 22 Aug 2001 21:32:56 +0200 |
> Uhm... so when using TIM1024T or TIM8T once per frame, I'd get a > reliable frame counter for free? No, that's not how it works. First of all the timer overflow should be active for all timers, it's just a matter of the lowest bit in the address to read it. Address $284 is INTIM and address $285 should be the timer overflow. But since some of the address bits are ignored when reading from the RIOT, reading from $294 (TIM1T) should be the same as reading from $284 (INTIM) for example. When a timer has reached $00 it stays at that for as long as the timer is selected (64 cycles on TIM64T) and then wraps to $FF. The timer then goes into TIM1T mode and keeps counting back. Everytime the timer wraps from $00 to $FF the interrupt flag is set (if timer interrups are enabled) and I think the timer overflow is increased or decreased. > Is the SEI at the beginning of most games unnecessary then? Not really. The 6507 has no interrupt connections on the outside, but the interrupt lines on the inside are still there. So theoretically it might be possible that an interrupt signal could accidentally be generated in the processor. Ciao, Eckhard Stolberg - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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