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Thread: Aim-65 video card mystery

  1. #21
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    This is the best photograph of the top of the buffer board I have been able to find:

    https://www.worthpoint.com/worthoped...fer-2001589385

    1 * 245 (data bus buffer) and 2 * 244 (address buffers).

    C2, C3 and C4 must be decoupling capacitors for the TTL ICs.

    I guess C1 is across the +5V power supply?

    Not sure what the single resistor does - or what the 3 resistor packs do yet...

    I see a link as well - possibly to isolate the +5V supply from the Aim-65 to the expansion bus?

    The schematic etc. is in here http://retro.hansotten.nl/uploads/fi...ch9%20RM65.pdf on page 9-88. The only thing missing now is the PCB layout...

    Although I have noticed that the TTL part numbers are different between the schematic and photograph - and the photograph has a discrete resistor that does not appear in the schematic.

    CORRECTION: The discrete resistor is on the schematic! Just found it...

    It looks like the difference between the photographs and schematic device IDs is that the 245/244 are non-inverting whilst the 640/240 are inverting. It looks like from the connector pinouts that the AIM-65 as an active high address/data bus whilst the RM65 is an active low address/data bus - so the inverting variants should be the ones to use for consistency...

    Dave
    Last edited by daver2; January 21st, 2021 at 08:27 AM.

  2. #22

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    Quote Originally Posted by daver2 View Post

    The schematic etc. is in here http://retro.hansotten.nl/uploads/fi...ch9%20RM65.pdf on page 9-88. The only thing missing now is the PCB layout...

    Dave
    Thanks for that link to the book !

    The schematic matches another photo of the card (attached that has two LS240 and a LS640). So from this I can replicate it. Though the tracks on the lower surface won't match the shape of the originals, but I might have a lead on who owns one of these pcb's, to get a solder side photo.

    edit: interesting value pull-up resistors at 22k, higher than typical. I zoomed up on the manual's image and they don't look like 2.2k.
    Attached Images Attached Images
    Last edited by Hugo Holden; January 21st, 2021 at 01:57 PM.

  3. #23
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    Getting there ...

    Dave

  4. #24

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    Quote Originally Posted by daver2 View Post
    Getting there ...

    Dave
    I like to replicate vintage pcb's as closely as possible, it seems to increase the probability of it working out.

    I have been looking into the DIN Eurocard connectors. They are actually a 3 row connector, but only have two of the rows fitted, rows a and c. This explains the pin numbering on the 64 way connector on the schematic too. Curiously the right angle plugs are a lot easier to get than the right angle sockets (receptacles). But I have found some from a local supplier.

    It also looks like the video output connector on the CRTC card is a right angle SMA type.

    Yes, slowly the puzzle is falling into place, it is looking very likely at this point I can get all the info to make it work.

  5. #25

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    The RM65 cards also came with an edge connector as well as the Euro type connector. It is just as valid and a lot easier to deal with. You might also look at using a bus rather than a single connector. It can be handy for adding RAM, disk or I/O ports. Of course, RM65 boards seem to be rare. I've never seen the edge connector type boards but I know they made them.
    Dwight

  6. #26
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    I see you have found some DIN connectors. If you run out, I may have access to some. I think I have right-angled male plugs (solder type) and straight female sockets (push fit).

    I bought 7,500 for a remanufacturing job, and may have a few left...

    Dave

  7. #27

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    Quote Originally Posted by Dwight Elvey View Post
    The RM65 cards also came with an edge connector as well as the Euro type connector. It is just as valid and a lot easier to deal with. You might also look at using a bus rather than a single connector. It can be handy for adding RAM, disk or I/O ports. Of course, RM65 boards seem to be rare. I've never seen the edge connector type boards but I know they made them.
    Dwight
    Dwight,

    I decided to use the Euro connector version on both the adapter and the the video board.

    The reason being that the adapter board would also be able to be used with the RM-65 RAM cards, which one day I might find, or replicate, and I could use those on the AIM-65 as well.

  8. #28
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    Quote Originally Posted by Hugo Holden View Post
    Dwight,

    I decided to use the Euro connector version on both the adapter and the the video board.

    The reason being that the adapter board would also be able to be used with the RM-65 RAM cards, which one day I might find, or replicate, and I could use those on the AIM-65 as well.
    If/when you want to replicate a RAM card, I can help as I have the 32k dynamic RAM module, manual and schematic. I also have the 8K static RAM manual and schematic but not the card.

    I can also try out the replica video board in my system when you make it.

    Santo

  9. #29

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    Quote Originally Posted by Hugo Holden View Post
    Dwight,

    I decided to use the Euro connector version on both the adapter and the the video board.

    The reason being that the adapter board would also be able to be used with the RM-65 RAM cards, which one day I might find, or replicate, and I could use those on the AIM-65 as well.
    The machine I have, used the Euro Cards but all of the boards were made available in both types. The cards with the E at the end were Euro card types and the ones without the E at the end were the edge. I think if you were going to make a bus, it would not be too hard to make it so that you could use either type of card. The wires all come out at the same order so bussing should be easy between the two types. It is then just making more holes. Since place usually quote by area, it would make sense to not lock into one or the other.
    I will have to admit, all that I've seen are Euro type cards.
    The machine I have was to use a ICE board ( likely for a 6502 or similar ) but I don't have the software or the dongle for it. The ICE board uses two busses. They are both Euro card types. For the price of shipping, I'd be willing to part with one of the busses. I need to check that that is what I have to make sure it is as I've stated but I know I'll never use the ICE board or the extra buss.
    Dwight

  10. #30

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    I don't recall if someone posted a pointer to the video card so here it is:
    http://retro.hansotten.nl/uploads/fi...Controller.pdf
    Dwight

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