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I wish to create a new DMA/RAM expansion card for the Tandy 1000 line.

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  • bladamson
    replied
    Originally posted by blackepyon View Post
    That might not be a bad idea, if we can agree on a common design. Probably a three-hole blank plate, with right-angle arms to mount to a 100mm board, and holes tapped for 6-32 threads. That way, you just get out the drill and dremel to modify them as needed for the application.

    Well, my boards just shipped, and should be here in a week or less, so I'll see if I got the measurements right.
    I have some ISA proto cards whose brackets have a break-out section (kinda like you see on electrical junction boxes) that's set up so you can break it out for different sizes of d-sub connector. It's a little ugly-looking, but something like that might be best? It's past my bedtime for now, but I'll try to remember to go up and take some pictures tomorrow evening and attach them.

    Barring that, I think if I was gonna cut very many with a dremel, I'd try to find someone with a CNC mill instead. =:3 Hmm although I guess if it didn't have to be exactly D-shaped, it could be done with only two plunge and cuts on a manual mill anyway.

    Leave a comment:


  • blackepyon
    replied
    Yeah, that's what the drill and a dremel are for.

    Leave a comment:


  • rkrenicki
    replied
    I just wish that D-sub punch dies were not $600+ a piece. I have two different projects that could use a DA sized and DE sized punch, but I do not have $1200 to spend on them.

    Leave a comment:


  • blackepyon
    replied
    That might not be a bad idea, if we can agree on a common design. Probably a three-hole blank plate, with right-angle arms to mount to a 100mm board, and holes tapped for 6-32 threads. That way, you just get out the drill and dremel to modify them as needed for the application.

    Well, my boards just shipped, and should be here in a week or less, so I'll see if I got the measurements right.

    Leave a comment:


  • bladamson
    replied
    Originally posted by blackepyon View Post
    I'd use a metal back-plane instead of PCB, but metal brackets are friggin expensive to get custom made at low volume.
    What qualifies as "not low volume"? Could several of us do a group buy?

    Leave a comment:


  • blackepyon
    replied
    Good thinking. Just line it up, and you've got your solution already made.

    Leave a comment:


  • dJOS
    replied
    Originally posted by rkrenicki View Post
    Honestly, it largely came down to cost. New CF connectors from Mouser are far more expensive ($9/ea) than these adapters (about $3/ea).. even with the cost of a 40 pin female header (about $1), it saves money and frustration from soldering these connectors. It also addressed my backplate problem at the same time. As much as I would like to take credit for the idea, it is the same solution that Monotech is using on their XT-CF cards nowadays. I am not sure if he uses the same adapter, but the concept is the same for sure.
    Still a great idea, I like it a lot.

    Leave a comment:


  • rkrenicki
    replied
    Originally posted by blackepyon View Post
    Nice! Did you recycle a PC bracket for that or get one made?
    It came with the CF adapter. I flattened it out and cut out a hole for the serial port. This is the adapter I used: https://www.ebay.com/itm/153609704829

    Leave a comment:


  • rkrenicki
    replied
    Originally posted by dJOS View Post
    Looks really good Robert - great idea adding the IDE header so that you can utilize an off the shelf adapter.
    Honestly, it largely came down to cost. New CF connectors from Mouser are far more expensive ($9/ea) than these adapters (about $3/ea).. even with the cost of a 40 pin female header (about $1), it saves money and frustration from soldering these connectors. It also addressed my backplate problem at the same time. As much as I would like to take credit for the idea, it is the same solution that Monotech is using on their XT-CF cards nowadays. I am not sure if he uses the same adapter, but the concept is the same for sure.
    Last edited by rkrenicki; November 11, 2019, 08:04 PM.

    Leave a comment:


  • blackepyon
    replied
    Originally posted by rkrenicki View Post
    I too finalized my design. My final prototype arrived today, and I quickly assembled one. I had to tweak the placement of one part and fix some of the silkscreen, but all in all it functions perfectly. I purposely did not flush mount the passives to help in disassembly if the need arose, so this particular unit has a sloppy look to assembly. Final dimensions are 98x125mm, and is 100% through-hole parts (with the exception of the PLCC UART, but the socket is through-hole). I may try to work out an SMD version in the future, but I am quite satisfied with the results as they are.

    [ATTACH]57277[/ATTACH]
    [ATTACH=CONFIG]57278[/ATTACH]
    Nice! Did you recycle a PC bracket for that or get one made?

    Leave a comment:


  • dJOS
    replied
    Looks really good Robert - great idea adding the IDE header so that you can utilize an off the shelf adapter.

    Leave a comment:


  • rkrenicki
    replied
    I too finalized my design. My final prototype arrived today, and I quickly assembled one. I had to tweak the placement of one part and fix some of the silkscreen, but all in all it functions perfectly. I purposely did not flush mount the passives to help in disassembly if the need arose, so this particular unit has a sloppy look to assembly. Final dimensions are 98x125mm, and is 100% through-hole parts (with the exception of the PLCC UART, but the socket is through-hole). I may try to work out an SMD version in the future, but I am quite satisfied with the results as they are.

    20191111_184809814_iOS.jpg
    20191112_001824317_iOS.jpg
    Last edited by rkrenicki; November 11, 2019, 07:09 PM.

    Leave a comment:


  • blackepyon
    replied
    Originally posted by Eudimorphodon View Post
    And yeah, this set is under the 100mm square mark.
    I've FINALLY finalized my PLUS version of the XT-IDE rev.4, and have submitted that to PCBWay for review. Revision 1, anyways, fingers crossed everything works, because I had to relay and re-route everything from the original to make it all fit the way I wanted. 140mm x 98mm, plus a 18mm x129mm back-plane soldered on at a right angle (gonna use 6-32 PEM nuts to secure it to the chassis).
    I'd use a metal back-plane instead of PCB, but metal brackets are friggin expensive to get custom made at low volume. The board would be smaller if I didn't have to worry about that guttter, and far smaller than that if I went SMD (but where's the fun in that), but I used the extra space to put in that rear-facing IDE header I wanted.

    If it all works, I'll put it up on Git-Hub. The soldered-on back-plane will be a handy template for future PLUS cards, if I didn't botch up my measurements. Fingers crossed.

    Leave a comment:


  • Eudimorphodon
    replied
    Originally posted by blackepyon View Post
    For this reason, I'm very selective on what parts I get off eBay.

    You still getting the 100x100mm $5 specials off PCBWay?
    In fairness I haven't tested the whole batch; the chip I tried is the one I had in it back when I had the "backwards buffer" problem, I probably shouldn't rule out that I could have zapped it somehow while probing. The flash chips I got from ebay have been fine, as has everything else, but maybe srams cost just enough to make it worth playing the floor sweepings game.

    And yeah, this set is under the 100mm square mark.

    Leave a comment:


  • blackepyon
    replied
    Originally posted by dJOS View Post
    On the EX, the pins are right next to the PLUS expansion slot and even have the pins installed (at least on mine they were). You can prolly get to them even without removing the crappy sheilding.

    If you leave them Open (default), they put +5v onto that pin.
    +5v through a 4.7k resistor for that jumper, so it's not for power. It looks like it's biased high and Pin-26 on the parallel array chip pulls it low.

    Originally posted by Eudimorphodon View Post
    Also, apparently Mister Black didn't get the only bum RAM chips from eBay.
    For this reason, I'm very selective on what parts I get off eBay.

    You still getting the 100x100mm $5 specials off PCBWay?

    Leave a comment:

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