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Thread: Aim-65 video card mystery

  1. #1

    Default Aim-65 video card mystery

    I found this image in some vintage AIM 65 documentation. It is a video card that plugs directly onto the expansion connector.

    Does anybody know the model number for this card, if a manual or schematic exists for it anywhere ?

    I'd probably be lucky to find one, but I could probably replicate it if I had the schematics.
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  2. #2
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    I am guessing (from looking at the photograph) that there are two parts to this.

    1. Is an adapter from the expansion bus to a ‘commercial’ bus.
    2. A video card for the ‘commercial’ bus.

    I remember a company in the UK made an adaptor card for the AIM and sold a range of expansion cards for it (including a floppy disk and a DOS).

    I have been trying to find an image of the DOS ROM for my emulator. No luck as of yet.

    I will see if I can find the link for you.

    EDIT: An interesting thread here: http://classiccmp.org/pipermail/ccta...ch/046465.html. It mentions the FDC and DOS in addition to a CRT controller along with the card reference IDs. Dwight is also mentioned by name...

    This link is also interesting: http://retro.hansotten.nl/6502-sbc/aim-65/rm-65/. It describes an AIM-65 adapter card for the Rockwell RM65 bus. I have even found the DOS ROM dump (possibly) and there is a block diagram of the CRT card (a basic 6545-1 CRT controller by the looks of it).

    Unfortunately, pictures of the adapter card appears to be a 2-board set with a cable in between. I wonder if the single adapter card came earlier or later, or from a different supplier?

    Here us the link I was thinking of http://www.vintagecomputer.net/fjkra...section_02.htm.

    Dave
    Last edited by daver2; January 17th, 2021 at 05:02 AM.

  3. #3
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    It's the RM-65 CRT controller. Here's a link with lots of pics:

    http://retro.hansotten.nl/6502-sbc/aim-65/rm-65/

    These cards came in an edge-connector version compatible with the AIM-65 directly, and a eurocard version. There were expansion bus options that provided multiple slots and buffering. On the above linked page, you can see a eurocard floppy controller connected to an AIM with a single-card adapter, which was also an option (I think this could also be used to drive a multi-slot backplane).

    I actually have this CRT controller, in the Eurocard flavor, just like the picture. Unfortunately, I don't have an adapter or a backplane system. Perhaps making one should be on the to-do list, but I keep hoping I'll come across one.

    Dave

    (Edit: I see daver2 has already added the link. I will check the manual, and will scan (or photograph) the schematics. Laying the manual flat will break the spine, so photographing and unwarping might be the best option.)
    Last edited by dfnr2; January 17th, 2021 at 07:41 AM.

  4. #4
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    I fired up my AIM-65 emulator this afternoon and I found that it already contained the AIM 65 DOS VERSION 1.0 ROM image.

    I remember now what the problem was - I couldn't make sense of the ROM contents when I tried following the manual...

    The initialisation entry point (at $8000) contained all $00 bytes and not valid code.

    I then assumed it was just the 'disk primitives' and examined memory at $886C (INIT) - but that also contained $00 bytes...

    I will probably have to read the FDC hardware manual (again) ...

    Dave

  5. #5

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    Quote Originally Posted by dfnr2 View Post
    It's the RM-65 CRT controller. Here's a link with lots of pics:

    http://retro.hansotten.nl/6502-sbc/aim-65/rm-65/

    These cards came in an edge-connector version compatible with the AIM-65 directly, and a eurocard version.

    I will check the manual, and will scan (or photograph) the schematics. Laying the manual flat will break the spine, so photographing and unwarping might be the best option.)
    The Hansotten site is where I found the photo of it plugged directly onto the expansion connector, the two versions of it explains that photo.

    Thanks so much for copying the information, looking forward to seeing it.

    In terms of getting this system up and running again on an AIM-65 there is one thing worrying me. Most likely somewhere (either on this video card in a ROM or a a file to load into the AIM-65 from tape) I would expect there would be a small program(firmware) to control the CRTC adapter, scrolling functions etc so the display would scroll normally, or maybe it was just done on the card itself ? I see on the RM-65 module there is a ROM on the board. If that is the case I would somehow have to find a dump of it if I was going to be able to successfully replicate the module.
    Last edited by Hugo Holden; January 17th, 2021 at 01:31 PM.

  6. #6

    Default

    Quote Originally Posted by daver2 View Post
    I am guessing (from looking at the photograph) that there are two parts to this.

    1. Is an adapter from the expansion bus to a ‘commercial’ bus.
    2. A video card for the ‘commercial’ bus.


    Unfortunately, pictures of the adapter card appears to be a 2-board set with a cable in between. I wonder if the single adapter card came earlier or later, or from a different supplier?

    Dave
    Yes, thanks, a look at the photo again, it looks like an adapter sits between the AIM's expansion connector and the actual video card.

  7. #7

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    Also, I think the same adapter would be required to use something like the add on 8k RAM board (which I want to make a clone of too) so it will be very good to find information on the adapter. The 8k RAM board info is here:

    http://cini.classiccmp.org/pdf/Rockw...s%20Manual.pdf

    I think these would be great projects for AIM-65 owners. I can draw up the pcb artwork and fund the pcb development. Maybe these adapters, and the 8k RAM card and the Video card would also work on a KIM-1 ?

  8. #8
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    I think this would be. a great project. I've had it in the back of my mind to make an adapter for the CRT controller, and to try to replicate the floppy controller.

    Another option, BTW, would be to interface to the OSI bus, for which there are video controllers, RAM, and a floppy controller. I know of at least one person who did that.

    Dave

  9. #9
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    Here's the schematic from the manual. Unfortunately, the forum limits the image size, so PM me and I will send you a higher quality copy.

    RM65-CRTC.jpg

    Dave

  10. #10

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    Hi Dave,

    Thank you. I sent a PM with my email on it.

    From what I can see so far it looks like it has a custom Character generator. Matrox did this with their ALTR-2480 video card, rather than using the pre-made ones like in the SOL-20 and VDM-1 card. I have the ALTR-2480 so the ROM from that could make a trial ROM.

    Also it looks like another ROM is on the card (maybe) probably the one with the firmware for scrolling the text.

    It might not be possible (for me at least) to replicate this without the original ROM dump. I wonder if anyone out there has one of these cards ? It would be a pretty rare animal I would guess. But it would be great to find one and be able to replicate it, before it gets lost to the sands of time, which might have already happened.

    Hugo.

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