Jim Brain <email@example.com> 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? > * At 7.4ms, ATN_IN goes high again > * ATNACK is already low, so DATA_ACK goes high > * DATA_OUT is already hi, so all is well A bit more detail for clarification/matching the events in the trace to the drive ROM: * the drive receives one command byte (0x3f - UNLISTEN) via E9C9 * at EA28 it sets DATA_OUT high (I hope I don't confuse high/low in here anywhere, I usually look at the serial bus instead of the driver inputs and sd2iec is also written in "bus level" style) * the received command byte is processed * at E902 the drive waits until ATN_IN is low * host sets ATN_IN low * ATNACK is set low at E8E0 * the LISTENER and TALKER flags are both not set, so the code skips to EA4E * DATA_OUT, CLOCK_OUT and ATNACK are all set to low there * EBE7 notices that a command or file name was received and starts to process it - which means the drive needs to read data from the disk to create a directory listing > * Than, at 9.443mS, ATN goes high again > * DATA never goes high, ever (which of the at least four DATA signals?) DATA_OUT won't move until the drive is actively looking at the serial bus again, but the hardware-acknowledge handles that case. DATA_IN and DATA_ACK both jump high at that point, so DATA_bus does go low. > * 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). > 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. -ik Message was sent through the cbm-hackers mailing listReceived on 2012-03-30 13:00:05
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