wille@frith.msu.edu (Jeffrey Wille) (09/06/90)
I am currently working on a project which involves data acquisition. I need to read the parallel port at an average rate of every 35 microseconds. Therefore, I really can't use interrupts. I don't think I can service an interrupt in 35 usec, and even if I could, I would starve my real-time data processing. What I would like to do, is put the data in a buffer, and have my A500 periodically empty the buffer in the tightest loop possible. I could tie a buffer empty signal to the pout or select line or something like that. I looked at the hardware RKM for some help, but found it terse at best. If someone could answer my questions, or direct me to a book with decent information, it would be appreciated. 1. How do I "own" the parallel port resources? 2. Am I required to use the ACK signal? I really don't need to use it but I was wondering if it must be asserted after the data strobe to reset internal latches, etc. If I must assert ACK, can I tie it to the data strobe? 3. How do I read the POUT and SEL pins? 4. How do I force the data pins to be always in the reading direction? I really don't want to deal with a bi-directional interface. 5. When the Amiga powers up, will there be any data on the data lines? (I don't want to blow any drivers by hooking up my device before I have a chance to tell the parallel port that it needs to be in reading mode.) I would really appreciate getting some answers to these questions, or being directed to a book that has the info I'm looking for. Actually, a book would be best. I am writing this in behalf of my brother, whose machine is not on the net. Please send your responses to rbw@spock.byu.edu if its not too much trouble. Thanks. no signature