On Mar 30, 2012, at 5:29 AM, Ingo Korb wrote: > Jim Brain <firstname.lastname@example.org> writes: > >> load"$",9 >> http://s15.postimage.org/pym7z9i23/with_ACK.png > > A bit small, but workable unless you need to decipher the timing marks. > >> http://s15.postimage.org/ar68ewq7b/without_ACK.png > > 180x100? Did you accidentally upload/link a thumbnail of the image you > wanted to show? He uploaded another copy of this one that is readable. http://s15.postimage.org/ciz79t9k9/without_ACK.png >> * ATN_IN cycles a few times (zoomFLoppy), trying to get a response. > > I don't see that in the screenshot? Besides, why would it have any > reason to wiggle ATN? It can tell that there is at least one drive on > the bus because DATA_bus went low within 1ms of ATN_bus low and there is > no timeout for any further response from the drive at that point because > it may currently work on a very long command (e.g. N or V). In the without_ack case, the DATA line never goes low so the ZF tries a few more times of toggling ATN before giving up and reporting "device not present". >> I don't understand why the DOS never notices ATN at 9.443ms > > It's busy reading data from the disk to create the directory listing the > host just asked for. That's an interesting idea. I did send Jim a special firmware that will wait forever for DATA to be acked. But perhaps it's never ACKed in this case since the ROM code expects the circuit to handle it? -Nate Message was sent through the cbm-hackers mailing listReceived on 2012-03-30 16:00:10
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