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Even though it is "off topic" I'll include my comment on this here... A device asserts INTRQ to say that it has moved from BSY=1 status to BSY=0 status (but not for all movements of BSY from 1 to 0) and when the host sees INTRQ asserted it should read the Status register (to acknowledge the INTRQ) -AND- if the host sees BSY=1 the device is BROKEN! No exceptions - the device is BROKEN! This applies to all commands including the EXEC DEV DIAG command.
First exception that leaps to my mind is what the host experiences when DEV was 1 when the op x90 EXEC DEV DIAG hit the bus and there is no ID = 0 device and the system in question pulls both INTRQ and BSY hi ...
Pat LaVarre
