Tutorial request: CIA timers

oRBIT · 11 June 2010, 13:46

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

Toni Wilen · 11 June 2010, 13:55

Only proper (any) OS compatible way is timer.device.

AlfaRomeo · 11 June 2010, 15:34

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

pmc · 11 June 2010, 15:43

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!!

AlfaRomeo · 11 June 2010, 23:31

Just in case interesting you:

http://cataclysm.cx/random/amiga/ref.../node012E.html

http://amigarealm.whdownload.com/com...ardref/apf.htm

11 June 2010, 13:46	#1
oRBIT Zone Friend Join Date: Apr 2006 Location: Gothenburg/Sweden Age: 48 Posts: 339	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

11 June 2010, 23:31	#5
AlfaRomeo A1200 040 SAM440EP 667 Join Date: Jan 2008 Location: Lisbon / Portugal Posts: 873	Just in case interesting you: http://cataclysm.cx/random/amiga/ref.../node012E.html http://amigarealm.whdownload.com/com...ardref/apf.htm Last edited by AlfaRomeo; 11 June 2010 at 23:37.

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11 June 2010, 13:55	#2
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,519	Only proper (any) OS compatible way is timer.device.

11 June 2010, 15:34	#3
AlfaRomeo A1200 040 SAM440EP 667 Join Date: Jan 2008 Location: Lisbon / Portugal Posts: 873	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

11 June 2010, 15:43	#4
pmc gone Join Date: Apr 2007 Location: completely gone Posts: 1,596	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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