Subject: Re: [stella] the B. Watson's problem... From: Chris Wilkson <ecwilkso@xxxxxxx> Date: Sun, 26 Aug 2001 16:13:56 -0400 (EDT) |
On Fri, 24 Aug 2001, Eckhard Stolberg wrote: > reading the timer only got me the interrupt register. Maybe I just > mixed up the bits when I tried to transfer their address information I think you did: > read and clear interrupt flag: RS-, R/W, A2, A0 = 1 Ok. > read interval timer: RS-, A4, A2, R/W, A0 = 1 read interval timer: RS-, R/W, A2 = 1: yes, but A0 = 0 (A3 enables/disables interrupt) > read interval timer overflow: RS-, A4, A2, R/W = 1; A0 = 0 This is the same as the corrected "read interval timer" above. I think you just mixed up A0 for reading the timer. In summary, if you're reading the the timer or the timer interrupt flag, the following applies: RS- = 1 R/W = 1 A4 = don't care A2 = 1 A1 = don't care A0 chooses between reading the timer or the interrupt flag: if (A0 = 0) => read timer => A3 controls the interrupt from the timer to IRQ- A3 = 0 => disables interrupt A3 = 1 => enables interrupt if (A0 = 1) => read interrupt flag => A3 = don't care => A3 = don't care -Chris - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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