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I've got this Apple to VGA adapter. I cannot remember what model this is for: it has got a male DB-15 pin connector at one side, and female DE-15 connector at the other side.

Female end of adaptor

Male end of adaptor

As you can see, it has got a row of 10 microswitches also.

I lost the instructions for this adapter long ago, so I'd like to ask, if anyone of you has a similar adapter, what is the purpose of those microswitches and which Apple models this adapter can work with.

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  • I remember 2-3-9 being the generic setting I started with with these devices, used these on everything from a Performa to a Desktop G3. The answer below by @traal is the exact same as the card from the back of the package.
    – PhasedOut
    Commented Jan 31, 2017 at 15:40

2 Answers 2

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I think this page (on archive.org) is about that adapter, which it calls the "AR5328 Apple to VGA monitor adapter." Other sources call it a "Mac to VGA adapter." It works with the Mac LC "pizza boxes," Performa, Quadra, etc. The switches are used to configure the adapter for the sync mode supported by the monitor (composite sync, sync on green, separate sync, etc.).

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    I've used this adapter to get an LC to talk to a 15" VGA monitor. The switches are tricky to use but it works.
    – Michael Shopsin
    Commented Jun 15, 2016 at 17:54
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    Any chance you could add the description of how the dip switches work so that your answer will still be useful when / if the link goes dead?
    – mnem
    Commented Jun 15, 2016 at 19:05
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    Adding value to this answer probably means ganking nearly that entire page. Not sure how the owner will feel about essentially reprinting their copyrighted stuff.
    – user12
    Commented Jun 15, 2016 at 20:09
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    It works on all beige Macintoshes, not just certain models. All of them have a DE-15 monitor port, and this will allow you to plug in a bog-standard VGA monitor.
    – Cody Gray
    Commented Jun 21, 2016 at 16:03
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    @MichaelShopsin The switches are not specific to a model. The dependency is the other way. Some older macs only recognize some resolutions and frequency range monitors, or even a limited selection of monitors. See my answer below.
    – Rowan Hawkins
    Commented Jan 30, 2017 at 19:55
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The switches are to tell the Macintosh Video Controller about the capabilities of the attached monitor when the monitor is NOT a Macintosh Proprietary Monitor. Macintosh Monitors individually perform the the position setting for their type so the controller knows what sync and resolution capabilities are on the other end of the wire, usually fixed for most Pre-G3 Macs.

The adapters started appearing in the early-mid 90's when sVGA Monitors capabilities were beginning to exceed those of the legacy Macintosh displays. Especially the large 17"-21" Glass tubes with the finer screen pitches which the Publishing industry was gravitating to. Other monitor vendors also made their own adapters to perform a similar function.

sVGA Monitors are essentially MultiSync, though Macintosh Multisyncs only have a narrow range they would sync within for each defined resolution. Apple finally made the switch to HE-15 output with G3 models.

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  • It's hard to think back to how things were then (even for those of us who have memories of those times), but it's important to realize that VESA DDC (and with it, EDID) didn't exist until 1994. Before then, display identification was pretty much the wild west: What standards did exist were poorly-specified and even less carefully followed, and the idea of buying any random monitor and plugging into a system it wasn't built for was as laughable as thinking you could stick an Amiga floppy disk into a Mac and be able to read the contents! Hence, box-o-cryptic-switches.
    – FeRD
    Commented Mar 3, 2020 at 6:23
  • It is not THAT cryptic. It was accomplished by tying pins together with resistors. Early Mac and other Monitors were single resolution and single frequency. This device allowed you to attach a later multi-sync monitor to the earlier mac system and let the device tell the monitor about its capabilities. A very similar thing exists in Microsoft's monitor.inf file which lists the capabilities of the monitor so that the video card sends signals in a way compatible with the monitor. I once wrote my own for a high quality fixed frequency CAD monitor with a .23 screen instead of .28 of the time.
    – Rowan Hawkins
    Commented Mar 3, 2020 at 6:57

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