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Thread: Multitech MGA adapter

  1. #1
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    Default Multitech MGA adapter

    New beastie came in the post today

    A full length Multitech MGA/CGA/EGA adapter - At least that is what the description

    The model is a Multitech PB85005-2A
    Has 8 16kb chips on board - so 64kb, and a rom.
    .
    I'm wondering if this thing is Hercules capable, but can't find squat on it at all.

    What is the difference between Hercules and MGA or is it 2 definitions of the same thing.

    I really don't think this is an MDA, as it's got more ram and again, the rom chip

    Anyone got any insight?
    Nothing beats the roar of a 36yr old drive coming to life after a decade in storagg

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    "MGA" is Hercules, it's just MDA with graphics support.

    Usually if it's multimode, there will be a bunch of switches on the back panel to select the display type.
    Some fancier ones are automatic-ish or software controlled like some of the ATI Wonder series.

    Edit: Quick note regarding video ram, if they're 4116's or equivilent, then that's only 16KB of RAM.
    Last edited by SpidersWeb; December 8th, 2020 at 09:58 AM.

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    Quote Originally Posted by SpidersWeb View Post
    "MGA" is Hercules, it's just MDA with graphics support.

    Usually if it's multimode, there will be a bunch of switches on the back panel to select the display type.
    Some fancier ones are automatic-ish or software controlled like some of the ATI Wonder series.

    Edit: Quick note regarding video ram, if they're 4116's or equivilent, then that's only 16KB of RAM.
    I'll have another look at it later tonight.
    Interesting thing about it is, in the 5150, it boots as a mono adapter
    Plug it into the 5160, even set to mono, no dice, just the beeps of no video
    Nothing beats the roar of a 36yr old drive coming to life after a decade in storagg

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    Bit of an update.
    I'm about to throw the thing out the window.

    I cannot get the graphics part of MGA to work, at all, on any of the cards i have
    SimCGA just makes the screen go black
    The SetCGA command afterwords, does the same thing until i type cls
    I am probably doing something wrong with it, unless i can figure it out soon, i may just end up paying ebay prices for an ega monitor or cga card + matching monitor.
    How does one properly setup a MGC + Mono adapter + Monitor?
    Nothing beats the roar of a 36yr old drive coming to life after a decade in storagg

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    There should be no setup beyond getting text to display.

    To test, try to find a program (e.g. Microsoft Flight Simulator) that supports Hercules graphics mode directly.

    P.S. I've never seen a Multitech -2A MGA. Most of them out there are the -7H models. I wonder if the -2A one is a very early (read: incompatible) model.

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    Quote Originally Posted by k2x4b524[ View Post
    The model is a Multitech PB85005-2A
    Has 8 16kb chips on board - so 64kb, and a rom.
    Just to be clear on something: "8x16kb" means either 16 Kilobytes if by "kb" you mean "kiloBITS", or it means 128k if by "kb" you mean "Kilo-Bytes". (8x8=64, 8x16=128. Maybe you should just post a photo of this thing. As for the ROM, that is probably the character generator ROM, not a BIOS ROM. All video cards of that era have one, including MDA and CGA cards.

    There are photos of similar Multitech cards online but none of them are clear enough to completely make out the memory. One version has 8 18 pin sockets, which implies it came with 64K in the form of 4 sets of 4416 16kx4 chips, while another one appears to also have 64K made out of a single bank of Fujitsu 8264A 64kx1 chips. Either is correct for a Hercules card-compatible card. And, yes, if your card looks like either of those two it has a character ROM, not a BIOS ROM.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

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    Quote Originally Posted by Chuck(G) View Post
    There should be no setup beyond getting text to display.

    To test, try to find a program (e.g. Microsoft Flight Simulator) that supports Hercules graphics mode directly.

    P.S. I've never seen a Multitech -2A MGA. Most of them out there are the -7H models. I wonder if the -2A one is a very early (read: incompatible) model.
    I actually got the thing to work with simcga, so i'm sure it is a herc clone. The game i got to work was Monument Of Mars

    Another thing, IBM Advanced Diags shows both an MDA and a CGA adapter, so i think this card is autoswitching based on what the system expects, like the dip switch set to cga, it will put out CGA

    Eudimorphodon - I will post a pic either today or tomorrow of the thing, and its floppy companion i have, a multitech PB85020 serial, clock, floppy controller.
    Nothing beats the roar of a 36yr old drive coming to life after a decade in storagg

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    The multitech is a bonafide herc card.
    IBM advanced diags sees both a mono and cga
    MSD versions 1 and 3 see it as a hercules card
    This thread can be closed
    Nothing beats the roar of a 36yr old drive coming to life after a decade in storagg

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