>>> 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.
At least the PATA version has a SFF (small-form-factor.. 2.5") variant of the connector. Its pitch is 2mm instead of 2.54 and it has 4 more pins (total of 44) for supplying power to the drive. I was designing last month a solid state disk in that size, by using CF cards :) >>> 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. You're right, it's non-standard. The IDE/SCSI (40/50) pin connectors have a square shaped grid, the connector on the OGD1 has a diamond grid for pins.. so even if you buy a ide/scsi connector, you can't place it there. (exception: if there are pins between the 4 pins of IDE, then you can effectively use only the half of the pins, but the pin layout seems to be different - i do not have exact pcb layout, just looking to the scans / jpeg of pcb). I would leave the connector out of the board and only specify in the docs the recommended types which will mechanically fit. This way an extension board developer can choose a pair of connectors which matches its needs - either with ribbon cable or without, using board-to-board option. Each of these advanced developers will have to build their extension board so they should be equipped with a technology to solder the IDC to OGD1. Then after a while when a popular ext. board will exist and TT/OHF will have more money they can supply OGDx with the IDC mounted on each pcb. Daniel _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
