> > > The connector we selected has two rows of 50 pins, and the spacing is > > > the same as a PATA IDE connector. I don't recall how many pins are > > > ground. > > > > The picture I'm looking at has four rows of holes. > > > > A standard 100 conductor ribbon cable would be about 127mm wide. > > The connector would be slightly wider. This wouldn't fit. > > The hole positions don't line up with the pins. That is, the PCB > holes are staggered, while the connector pins are not. Also, the > connector we chose has a right angle so that the pins are parallel to > the PCB. > > > Did you mean 2 50 conductor cables? Then the 4 rows of holes > > would make sense, and it would fit. > > Well, that's one thing. When we talk about an 80-conductor IDE cable, > we note that 40 of those conductors are actually ground. Indeed, > IIRC, a whole row of pins for IDE are ground. That isn't the case for > us. At least 70 of the pins on our connector are data. > > > There are smaller ribbon cables. Newer PATA cables have 80 > > conductor ribbon cables connected to special 80-to-40 pin connectors > > with standard pin spacing. > > I'm not sure of the details of all of that, really.
Older PATA cables use standard 40 conductor ribbon cable and standard IDC connectors. But since PATA isn't terminated the signal quality wasn't good enough as speeds increased. So they switch the cable to a nonstandard one with 80 conductors in the same width as a standard 40 conductor ribbon cable. IIRC they ground every other conductor in addition to whatever pins were ground on the original. But they wanted to stay compatable with older PATA, so the connector is still 40 pins with standard spacing. IIRC laptop drives (both PATA and SCSI) use nonstandard ribbon cables including the connector. > > If these holes are thru-hole, connectors (or just pin headers) > > could be added in the field. If they are surface mount, > > soldering the inner rows could be tricky. > > They're through-hole. There are these clips that you can get to crimp > onto wires and then push into the holes, if you like. > > > If these are standard IDC connectors, they shouldn't cost that much > > relative to a "at least $1500" OGD board. > > True. IIRC, it's something like $30. But keep in mind that the price > we're trying to keep down is the dev price. We still need to make a > small profit from those. This must be some nonstandard connector. Standard IDC connectors or pin headers would be lots cheaper than this. I assume there must have been some reason to not use something like 2 50-pin pin headers or connectors, as used for narrow SCSI? A couple minutes with Froogle found: $0.436 50 pin pin header $0.596 50 pin right angle pin header $0.75 50 pin low profile shrouded box header $1.19 50 pin board mount female connector That's for quantity 1. Larger quantities and more searching would likely find even lower prices. _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
