VOGONS

[SOLVED]RTC Periodic Interrupt Enable problem

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First post, by AndrejaKo

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I'm making a program which will use interrupt 70h/IRQ8 from RTC.

Using the DOSBox debugger, I've confirmed that I'm writing right value to RTC's registers A and B so that periodic interrupt should be enabled. I've also confirmed that the periodic interrupt flag in register C gets set and that the programmable interrupt controllers are set so that master PIC is accepting interrupts from slave PIC and slave PIC is accepting interrupts from IRQ8.

The interrupt handler (at this point) just displays a message on the screen and that works when I call the int 70h by hand. The problem is when I set the test program to loop infinitely at its end in order to wait for the RTC interrupt, nothing happens.

So does anyone happen to know the level of support for RTC periodic interrupts in DOSBox at this time?

Last edited by AndrejaKo on 2012-01-02, 21:25. Edited 1 time in total.

Reply 1 of 3, by h-a-l-9000

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Some games use it and work

1+1=10

Reply 2 of 3, by wd

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Be sure your rtc and irq acknowledging is correct.

Reply 3 of 3, by AndrejaKo

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THANKS A LOT GUYS!!!! In the end , the problem was a really stupid bug. I read the values from register B and then when I was supposed to write them back, I forgot to set the value I'm outputting at address 70h to 0xB! And of course, the register B didn't get the value I was expecting.

I was about to give up on this but your confirmation that it does indeed work as it should gave me a morale boots so instead of giving up, I caught and smashed the bug.

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