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VBL interrupts (was: Ok, anyone started Contiki 4 AII yet?)



CHRIS MORSE a �crit:

On Tue, 18 Mar 2003 10:40:07 -0500, Yves McDonald
<""yves.mcdonald\"@NO SPAM sympatico.ca> wrote:
Some good news for //e, 2c users! From a quick look in my //e Technical book (Apple/Addison-Wesley edition), there is an interrupt associated with Vertical Blanking (every 16ms) and OS interrupt support with ProDOS 8. The bad news: sorry for ][+ users but there are no built-in interrupt sources, altough a clever hardware hack exists to get vertical retrace interrupts (REF: Jim Sather, Understanding the Apple II, p.3-19 to 3-26). I guess Apple ][ users will have to provide their own timer interrupt services. 

Cheers,

Yves



So how do you access the vertical retrace interrupt? :)
I was reading last night in Rodnay Zak's book "Programming The Apple
II In Assembly Language" and in the section on programming the mouse,
there are a couple of interrupt services with the mouse card, with one
being tied to the vertical retrace (60Hz).

I hope I can find a //e Tech Ref manual.  I keep checking eBay.  But I
did order the //c Tech Ref manual (2nd ed, covering the //c+ also)
from A2Central.  Unfortunately, they say 6-8 weeks for delivery.

I used to have a TimeMaster II H.O. card, and I recall it able to do
60 interrupts/sec also.  Probably the same vertical retrace thing.

Will be interested to hear more! :)
It is hard to tell, even with Apple 2e Tech. Manual because the information is scattered across the whole book. From what I have gatehered so far, it is tied to 80-column hardware/firmware and toggling paddle/joystick timers resets vertical retrace interrupt. I still don't know how to activate it - maybe go in 80 columns mode? I'll have to dig myself. The answer may hide in the 80column card firmware which is listed in the Manual. 
A search in Apple 2 programming FAQ may bring info as well.
TTYL,