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Old 11 June 2010, 13:46   #1
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Tutorial request: CIA timers

Anyone got a tutorial (asm, for newbies ) somewhere concerning CIA timers?
I'm interested in setting up a 50/60Hz interrupt using CIA but haven't got a clue sadly.

(Btw: What's the proper way of setting up such an interrupt that's compatible with OS4?)

Thanks in advance
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Old 11 June 2010, 13:55   #2
Toni Wilen
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Only proper (any) OS compatible way is timer.device.
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Old 11 June 2010, 15:34   #3
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I have a tutorial about CIA from the banging the metal tutorial of AmigaFormat 124 but it doesn´t mension how to make interrupts from CIA
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Old 11 June 2010, 15:43   #4
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I know it's covered in the HRM.

From memory, *I think* it (very briefly) works something like:

patch the correct interrupt vector with the routine you want to run whenever the countdown timer expires

set the required CIA for continuous countdown timer

write the required time to countdown from to low timer byte and high timer byte (writing high byte starts the timer)

An interrupt will occurr every time the countdown timer expires and execute your interrupt code.

Like I say though - this is just from memory - I would need to check the HRM and try a few things out to be sure...

EDIT: Forgot to say - this is the hardware banging method - *not* OS friendly!!
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Old 11 June 2010, 23:31   #5
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Just in case interesting you:



Last edited by AlfaRomeo; 11 June 2010 at 23:37.
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