Mac IIci, System 7.5 and BNC x5 Video

Discussion in 'Apple' started by David Flory, Nov 15, 2006.

  1. David Flory

    David Flory Guest

    Hello everyone,

    I use an old Mac IIci for Apple II <-> PC transfers and messing around
    with vintage software.

    The 13" Mac Color Monitor is getting a bit troublesome, and I would like
    to try using the computer with an old multiscan VGA monitor using BNC x
    5 input. The apple video modes are all within its specs.

    Will the Mac video work properly if I simply use a DB-15 to BNCx5 cable?

    If the Mac can't get (or gets incorrect) sense data from the monitor,
    can the user set the monitor type manually?

    I appreciate any help,

    David Flory, Nov 15, 2006
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  2. I wouldn't spend a lot on that cable.

    This stuff was never my strong suit, and I'm pretty rusty, but I think
    that a BNC-5 uses a separate V and H sync, while the Mac uses sync-on-green.

    Not all DB-15 to BNC cables are exactly the same, and I recall somewhat
    pricey boxes to convert sync options back and forth.

    My guess is that it won't work, but "it depends" on a bunch of stuff...
    James Glidewell, Nov 16, 2006
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  3. Thanks, that's good advice.

    I think my monitor can do sync on green if it has to...but I'm not
    really expecting it to work. I did hear somewhere that the IIci onboard
    video only works with a few Apple monitors.

    Are there any Nubus video cards that are more multisync friendly?
    David A. Flory, Nov 16, 2006
  4. I never had a IIci, but I would expect it to work with almost any multisync
    monitor with a DB-15 input through a passive adapter. My reasoning here is
    based on the fact that a ci could definitely drive a Apple 13", as could
    models all the way up through the 8500 and beyond, so there is at least one
    mode (640X480) that should work.
    Who the heck remembers?

    The problem you are trying to solve is one that very few folks ever dealt
    with, and of those that did, last did so ten years ago or so.

    This is clearly a case where searches of and,
    with the words "mac" and the specific model number of your monitor are far
    more likely to get you an answer. Without an exact model number, and a
    fair amount of research, no one here is likely to be able to answer your
    question with any amount of confidence.
    James Glidewell, Nov 16, 2006
  5. David Flory

    Hauke Fath Guest

    If this is a Macintosh-style 15 pin connector, the cable will most
    likely come with either a fixed monitor code (which may or may not fit
    the capability of the IIci), or with built-in DIP switches.

    Otherwise, if it is a three-row compact 15 pin VGA style connector, you
    need an adapter anyway which then has to have the DIP switches to set
    the proper monitor encoding.

    For all I know, the IIci does not do sync on green. Yes, very early Mac
    II Nubus video cards did that.
    No. There were later Multisync monitor codes that allowed you to adjust
    the resolution in the Monitors control panel, but the IIci does not
    support those.

    Hauke Fath, Nov 16, 2006
  6. David Flory

    Steve Hix Guest

    Mine, and my wife's IIcx, both used sync-on-green. IIRC, they both had
    the same SuperMac video card driving a 19" grayscale monitor, probably
    also a SuperMac. It has been more than a couple of years, I might
    misremember the manufacturer.
    Steve Hix, Nov 16, 2006
  7. Thank you very much, that is exactly what I needed to know.

    David A. Flory, Nov 16, 2006
  8. David Flory

    isw Guest

    The IIci had built-in video; with the IIcx you had to use a NuBus card,
    so the monitor requirements were card-dependent. IIRC, the ci only had
    one resolution using the built-in video (it could support a NuBus video
    card too, and give you a two-headed Mac if you wanted; I remember just
    blowing away a couple of researchers from the IBM San Jose operation by
    showing them that in about 1992).

    isw, Nov 17, 2006
  9. David Flory

    David Flory Guest

    That's funny! Thanks.
    David Flory, Nov 17, 2006
  10. David Flory

    David Flory Guest


    I always turn Google upside down and shake it before posting on usenet,
    but I got all the info I needed here.
    David Flory, Nov 17, 2006
  11. David Flory

    Hauke Fath Guest

    For your convenience, I have underlined the difference between the OP's
    setup (the IIci has onboard video, unlike previous Mac II models), and

    Hauke Fath, Nov 17, 2006
  12. David Flory

    David C. Guest

    Are you talking about the built-in video port or a nuBus video card?

    If it's a nuBus card, then you're at the mercy of the card's

    If you're talking about the built-in video, Apple's spec sheet says:

    A IIci can generate only two resoltions: 512x384 and 640x480. 1-, 4-,
    or 8-bit color.

    (I seem to remember also getting 800x600 out of a IIci, but maybe my
    memory is mistaken)

    These model Macs use three "sense lines" on the DB15 connector to know
    what the monitor's capabilities are:

    If your cable/adapter is designed for a specific monitor, then it will
    have the sense pins hard-wired to report the capbilities of the matching

    If your cable/adapter is generic (designed for many kinds of monitors),
    then it should have some switches you can use to explicitly set the
    sense codes. Hopefully you will have some documentation for how to set
    the switches. Set it for "640x480 @60Hz" or "Apple RGB 12" Monitor",
    and you should be OK.

    -- David
    David C., Nov 18, 2006
  13. David Flory

    Hauke Fath Guest

    It also supports 640x870 (4 bit) for a portrait monitor, see e.g.

    Hauke Fath, Nov 23, 2006
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