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OK, granted, not many people make their own cables any more; most Mac users will purchase the requisite cables to connect their various system components. Sometimes though, managers of larger Mac-user facilities, as well as most techy-types, have cable fabrication capabilities and thus have the opportunity to save a few bucks per cable. The most frequent requests I've had for information are to interface to multiscan VGA monitors and modems.
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How to Connect Monitors to a Macintosh - Part 1(If you have a large [17"-21"] VGA multiscan monitor, use this section, else go here.)If you are fortunate to have a system (G3 or PowerMac) that supports multiple resolutions up to 1024x768 or even 1152x870, and have one of the new multi-sync monitors like a Viewsonic, Hitachi, or RasterOps, use the conner RasterOps, use the connector adapter shown below:
This adapter will allow you to use the resolutions button of the Control Strip to select any resolution from 640x480 to the max resolution, on-the-fly. How to Connect Monitors to a Macintosh - Part 2(Quadra, Centris, and later models)The Mac Centris, Quadra, and later systems frame buffer determines what type of display is attached to the video connector by examining the state of 3 sense line pins. The following chart details how these three pins must be wired for each of the supported display types. For each supported display, the screen resolution (horiz. pixels X vertical pixels), bandwidth, and the vertical and horizontal scan rates are given. For the wiring of the rest of the pins, refer to Macintosh Video Pinout and your monitor's documentation. The Mac Quadras, Centris series, and later models should support any display, whether from Apple or from another vendor, that meets one of the following specifications:
STANDARD SENSE CODES (1 or more of the sense pins grounded):
Notes: 1) Sense pins 4, 7, and 10 are referred to as MON.ID1, MON.ID2, and MON.ID3 in the Macintosh pinout table or SENSE0, SENSE1, and SENSE2 in pinout tables for the video connectors. A sense pin value of 0 means that pin should be grounded to the C&VSYNC.GND signal (pin 11); a value of 1 means do not connect the pin. (See Macintosh Video Pinout ) 2) Extended sense codes will be examined if the following sense code is detected: 1 1 1 (no sense pins grounded). 3) The terms 'underscan' and 'overscan' are used to describe the active video resolution for NTSC and PAL modes. Underscansolution for NTSC and PAL modes. Underscan means that the active video area appears in a rectangle centered on the screen with a black surrounding area. This ensures that the entire active video area always is displayed on all monitors. Overscan utilizes the entire possible video area for NTSC or PAL. However, most monitors or televisions will cause some of this video to be lost beyond the edges of the display, so the entire image will not be seen. 4) The Apple 16" Color Display should have pins 4 and 10 tied together and pin 7 should be unconnected. If used with a Macintosh Display Card, the Apple 16" Color Display also requires the Macintosh Display Card 4*8, 8*24, or 8*24 GC with revised ROMs.
EXTENDED SENSE CODES (enabled by not grounding any sense pins)
NOTE for extended sense codes: Sense pin pair value of 0 means those pins should be tied together (as opposed to grounding 10, 7, or 4 to pin 11); value of 1 means leave open. DON'T wire any of these pins to ground.
Macintosh Video Pinout:
IF YOUR MONITOR IS A VGA TYPE, YOU CAN SIMPLY TRY THE FOLLOWING CABLE PINOUT: A cable wired as follows may allow many different brands of VGA monitors to work on a Macintosh. Test the monitor on a Macintosh prior to purchase to see if it meets your expectations. Basic VGA Adapter:
There are a few issues to keep in mind with VGA monitors: * VGA monitors will vary depending on the vendor. Check with the vendor about Macintosh compatibility before buying, or better yet, actually try the monitor to see if it works and if the quality is acceptable. * Vendors have different image quality specifications. There may be significant differences between Apple monitors and the wide range of VGA monitors. Do a side-by-side comparison of the monitors you are considering before buying. * Many third party cable vendors have off-the-shelf cables that should work.
MACINTOSH TO NTSC VIDEO CABLE EXAMPLE:Most NTSC devices use an RCA-type phono connector and the following diagram uses that as a reference point. A cable wired as follows may allow many different brands of NTSC monity different brands of NTSC monitors to work on a Macintosh Centris or Quadra. We advise you to test the monitor on one of these machines prior to purchase to see if it meets your expectations. Adjust the phono connector side to whatever type of connector is used (RCA, BNC, etc.). "Tip" is the pin in the center of the connector (the signal); the sleeve is the flange around the outer edges of the connector (the chassis ground).
By grounding pin 4 and pin 7 By grounding pin 4 and pin 7 to pin 11, the Macintosh CPUs are told that an interlaced (NTSC) monitor is attached. The actual black and white video signal is on pin 5 and connects to the center (Tip) of the phono-plug. The shell of the card connector connects to the sleeve of the phono plug. To acquire a color NTSC signal from a Quadra (or any Apple Macintosh display card), an RGB-to-NTSC converter is required, such as those available from RasterOps, Truevision, and Computer Friends. |
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