Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!sdd.hp.com!usc!apple!vsi1!daver!bungi.com!news Newsgroups: comp.sys.nsc.32k Subject: Re: my pc532 is almost up. Message-ID: Date: 25 Aug 90 04:46:30 GMT Sender: news@daver.bungi.com Lines: 40 Approved: news@daver.bungi.com Well, maybe it's not so close to being up after all. The LEDs start out with both pads at +5V and shortly after reset the pads nearer to the 6250 drop to GND. So, I am pretty sure that the LEDs and 6250 are fine. However, the ICU is not looking so good. I wish I could send you an email polaroid of the scope display, but I'll do my best with a 80x24 display... ---- - ---- - | | | ________________ ------| | | |_| |__/ |_| This is what the data lines from the 646 and into the ICU look like. The bottom line is 0V the next one up is 2V the near top one is about 4.5V and the top is 5V. All 8 data lines look like this. The 646 input data lines look much better, but have gliches on them and have several short pulses that are only about 1V tall... (like this [I hope]) -------------------- -------------------- | | | | | _ _ _ | |__| | | |__| those small pulses at the bottom are roughly square and about 1V tall, but other than that I think it is reasonable. And, just to make sure you don't interpret the / wrong in the first signal, it does ramp up to about 2V, kinda like there is a cap on it and some resistors to pull it to 2V and then the data line gets tri-stated. But the edges from 2V to 4V and 4V to 5V are very sharp. I believe that both signals as drawn are about 20uS from start to finish, and they are regular. (I am not beside the scope right now, and I don't remember the setting, but I believe it was 2uS/div with about 10div across the display...) Is this the way it should look??? I am not really used to seeing digital signals that run to 2V and 4V, but then I can imagine that I could make it happen without too much trouble if I wanted to. Any ideas? I am always open to suggestions, esp. now! -- Jon Buller jonb@vector.lonestar.org ..!texsun!vector!jonb FROM Fortune IMPORT Quote; FROM Lawyers IMPORT Disclaimer;