biswa@janus.Berkeley.EDU (Biswa Ghosh) (12/21/90)
Hi Folks, Believe it or not, I *finally* got around to assembling by sid-ii device. And, it doesn't work. Aack! I've found the following problem, and it seems to be with the modem/printer ports on my SE/30. The sid is parasitically powered from the TXD+ and TXD- outputs on the ports (pins 8 and 5 respectively). They are supposed to be differential outputs, so that when one is positive, the other is negative. Problem is, they are both sitting at +2.7V all the time, so my sid only gets a 2.7V supply. How can I get the outputs to be differential, so that the sid can get the +5V that it needs? I made the measurements both with and without the sid connected, with nothing connected to the other port, and the result is the same on both ports (i.e., txd+ and txd- are both positive). Any ideas? Biswa Ghosh 550 Cory Hall arpa: biswa@janus.berkeley.edu U.C. Berkeley uucp: ...ucbvax!janus!biswa Berkeley, CA 94720 tel: (415) 642-0395