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Posted by: Mars478 on 2009-09-12 08:17:47
A DB-15 to VGA adaptor with DIP switches! I'll keep this one in NJ and my other non DIPPED one in NY .
Is there any advantages to having DIPs?
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Posted by: JRL on 2009-09-12 08:18:33
You can adjust the adapter to work with different resolutions.
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Posted by: II2II on 2009-09-12 11:46:00
The DIPs are historical artifacts. Until the early or mid 1990s, most monitors used a fixed frequency. For all intents and purposes, this meant that a monitor ran at particular horizontal and vertical resolutions. If you wanted to use a higher resolution, or have a higher refresh rate, you would need to use a different monitor.
Which raises a problem: how do you figure out what type of monitor is attached to the computer? In the really early days, a video card would just assume that a compatible monitor was attached. Some vendors allowed you to select the resolution and refresh rate from a control panel. Yet other video cards had a piece of firmware that allowed you to select an approximate resolution and refresh rate during boot. But Apple selected a different route: let the monitor tell the video card what it is.
I think that modern monitors tell the video card about itself by sending a signal down the video cable. But that presents a couple of problems. Old monitors had a physical shutoff switch. Turn the monitor off, and none of the circuits have power. So a powered down or unplugged monitor could not tell the computer what it is. The other issue is that the electronics to generate that signal would add an extra cost to already pricey equipment. So Apple decided to connect particular pins together. Each pin combination representing a different monitor type. The computer could scan the pins, even when the monitor was turned off. Of course, to properly use a PC monitor the adapter would either be hard-coded to a particular monitor type or use dips to allow the user to select the monitor type.
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Posted by: Mars478 on 2009-09-14 14:02:46
Well Whaddya know? I found another one in the depths of the lab! This one has 10 DIPS and no instructions on how to use them, while my other one does.
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Posted by: porter on 2009-09-14 14:28:31
Well Whaddya know? I found another one in the depths of the lab! This one has 10 DIPS and no instructions on how to use them, while my other one does. http://myoldmac.net/FAQ/RGB-VGA-DIP-switchconfiguration.htm
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Posted by: joshc on 2009-09-15 23:37:24
Well Whaddya know? I found another one in the depths of the lab! This one has 10 DIPS and no instructions on how to use them, while my other one does. http://myoldmac.net/FAQ/RGB-VGA-DIP-switchconfiguration.htm
While useful, that page doesn't apply to all adapters. I've found the best adapter for use with any old Mac is the Mitsubishi AD-A205 - it has the instructions for the different resolutions on the back of the adapter.
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Posted by: Mars478 on 2009-09-16 04:29:39
Yep, one of my adaptors has the instructions on how to use the DIPS on the back of the adaptor. I'll check if its a mitsu
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Posted by: Bunsen on 2009-09-21 15:45:08
Apple selected a different route: let the monitor tell the video card what it is. Macintosh Displays: Overview of Sense Codes and Adapters
Quadra Series, Centris Series: Displays, Video Pinouts
Macintosh Monitor Sense Codes: Technical Description
Apple Discussions: Topic : Mac to VGA Monitor adapter settings needed
Do I have to power down the machine each time I disconnect the cable and change the settings, connect and restart the machine for it to recognize a signal?
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