A few points: - AFAIK the T200 uses the same connector with the same issue as the T102, so the M100 is actually the only one using a DIP plug/socket for the system bus connection.
The confusion stems from the fact that when looking into the pin side male and female connectors are reversed so that e.g. the top left pin mates with the bottom left socket (think about it ;-) and the DVI male pins are numbered the same as a female socket. The other issue is that the pins on an IDC DIP plug can be arranged either way, relative to the cable. The bottom line is that regardless of numbering the M100 cable has to connect pin 1 of the DIP plug to pin 1 of the 2x20 pin header; the headers are usually standardized so that pin 1 is the first wire in the cable, but DIP plugs come either way, with the most common having pin 1 connected to the second wire. If you look closely at the connector in the eBay ad that Brian posted you'll see what I mean. So, if your DIP plug connects pin 1 to the first wire in the cable (and the header does the same) then you're in business; a straight-through cable is all you need. If the header plug has a locating stub make sure it's on the side with the odd-numbered pins. If the DIP plug connects pin 1 to the second wire (pin 2 on the header) there are a couple of solutions: One approach is what Radio Shack did for the T102 & 200, which had the same issue of a male-to-female cable: swap every pair of wires so that the odd and even pins are swapped (i.e. 1 becomes 2, and 2 becomes one, etc.) Another solution is a second cable that swaps the pins; a normal 40-pin cable with female connectors at both ends (as used for older PATA hard disks) and a 40-pin chassis header with pins on both sides to connect the two cables together. Confused? I sure was when I first ran into this issue, and occasionally still am... m ----- Original Message ----- From: Randall Kindig To: [email protected] Sent: Monday, October 16, 2017 10:06 PM Subject: Re: [M100] DVI cable Brian, thanks so much for the detailed information! Randy On Oct 16, 2017, at 10:00 PM, Brian White <[email protected]> wrote: Well since no one answered any better, what I gather from the various manuals available on-line, my own dvi which came with a hand-made cable for Tandy102, and pictures of another hand made cable for 102 on ebay once a couple years ago... (I don't have a cable for Model 100, and have not yet actually built and tested this for Model 100) Parts (For Model 100 or 200, but not 102): * One 40pin dip idc connector like this: http://www.king-cart.com/cgi-bin/cart.cgi?store=phoenixent&product_name=HWS15322 or http://www.ebay.com/itm/162482138557 * One regular 40pin female idc connector, with polarity notch and strain-relief http://www.king-cart.com/phoenixent/product_name=HWS1877 * 20 inches of 40pin ribbon cable. Assembly: * Crimp the cable in the dip connector such that if you are looking at the dip connector with the #1 pin top-left and pins pointing away from you, the cable exits to the right, red stripe on top. This last part I'm not 100% sure about for Model 100 only because I haven't actually tried it. For a 102, I do know you have to take one end of the cable (doesn't matter which), and peel the conductors apart into 20 pairs, and flip each pair over before crimping the idc connector together. For a 100 or 200, I think you just run the cable straight through. The dip idc connector that goes in the 100 does not connect pin X to the same conductor Y as regular idc connectors. A regular idc connector connects pin 1 of the connector to conductor 1, and pin 40 to conductor 2. The dip idc connector reverses that. Pin 1 goes to conductor 2, pin 4 goes to conductor 1. I think the only reason you have to swap pairs over on a Model 102 cable is because they designed the pinout in the DVI so that a simple straight cable would work to a model 100 (same way they did for the printer port on the m100), and so to connect a 102, you have to artficially mimic the flipped pinout of the dip connector. Reference, "Style 2" from this drawing: https://media.digikey.com/Renders/Assmann%20Renders/partnumber%20breakdown%20Assmann.jpg "pin #1 on connector is connected to 2nd conductor on cable" I mean, I know for sure what a regular idc connector does, and what these dip idc connectors do, and what a working cable for a 102 looks like, and so from those I am deducing what the 100 cable must be. * Arrange the cable on the 40 pin idc female connector such that the end of the cable ends on the side of the connector with the polarity notch, and the cable extends away from the connector on the side opposite the polarity notch. Crimp the cable. Then fold the cable back over the top to snap on the strain relief clip. Now the cable is going the same direction as the key notch. References: * http://tandy.wiki/Disk/Video_Interface o Pictures of ebay cable, the original ad sold it as a T102 dvi cable. My own t102 cable is made a different way, but wired the same. o User manual page 9 (pdf page 13) o Service Manual figure B-1 system bus pinout * ftp://ftp.whtech.com/club100/doc/m100ServiceManual.pdf o figure 4-3 system bus pinout * https://www.digikey.com/product-detail/en/assmann-wsw-components/H0PPH-1006G/H0PPH-1006G-ND/1000156 -- bkw On Sun, Oct 15, 2017 at 11:23 PM, Randall Kindig <[email protected]> wrote: Does anyone have a cable for connecting the M100 to the DVI box (for composite monitor hook-up and disk drives)? Does anyone have information for making one? I know that Ian Mavric was looking into making a cable for this great M100 accessory, but I thought I would ask the list. thanks Randy
