Multiple Scan 15AV

Older Genuine Apple displays with the 15 pin (two-row) connector use pins 4, 7, and 10 to pass a monitor type code to the Mac at startup. That code is generally wired into the computer-end of the cable. This is intended to get you reasonable results without damaging your monitor when using a genuine Apple display.

I do not know for sure, but my impression is that with Windoze, you set it to whatever you say it should be and that's what it is. If you set it to something that does not display, tough beans. That's just like typing the wrong thing into your Autoexec.bat or Config.sys file. If it no longer works, too bad, you should have been more careful.

In a Mac, you must use a Mac-specific display card. The Matrox sounds vaguely familiar -- is it a PC-specific version?

I doubt that Windoze uses the Apple type codes, they seem to be special to Apple displays.

On later displays with a 15-pin (three-row) connector, several of the pins were reserved for a Digital Data Channel (DDC), a serial side channel that allowed information to be sent to the Computer concerning the display's capabilities.

Eventually, lots of display makers adopted it and it (DDC) became the standard. Eventually, Apple got on board with it around the time of the early G4's.

If you are using the original 15-pin (two-row) cable, it is capable of supplying the code, but I don't think Windoze will read it or do anything with it.

And I am pretty sure that display pre-dates the use of the DDC channel, so it seems like for Windoze, it will not tell the computer its capabilities, and you will have to set them by hand.

One hint: Apple Multiple scan displays can all do 640 by 480, in addition to their higher resolutions. Number of colors makes no difference to the display, it is only of interest to the display card, for how many VRAM bits to commit for each display pixel.

First, try to get a picture, any picture, and then work up to a higher resolutions. Start with 640 by 480 because the Apple MultiSync displays can all do that. Once you get a stable picture on it, Windoze Control Panel, like the Mac Control panel, gives you a trial of a different resolution, and you have to click OK (on the different resolution screen) or it times out and goes back to what it was previously.

Do not anguish over the amount of colors. The colors are sent as varying analog levels of Red, Green, and Blue. That makes no difference to the timing of the signals sent to display.

Video-philes assure us that Video signals can be plugged and unplugged "live". No need to shut down to swap CRTs.

Those aren't drivers in the usual sense -- they are more like descriptors -- telling what resolutions at what frequencies are supported by a given monitor.

Monitors accept video data or its Red, Green, and Blue inputs, and displays one horizontal line between HSync pulses, and retraces back to the top in response to VSync. It is not a very complicated protocol.

You should be able to set them by hand. The display capabilities are here:

http://docs.info.apple.com/article.html?artnum=112539

Craigwd_2000,

You are caught in what I call the dance of dualling standards. Put simply, Macs are smart computers, PCs are dumb. Bill and his buddies said 'we are smart so we will tell the computer every little thing to do in our own customized way.' So, you have to know all the codes and instructions on a PC.

Steve Jobs said 'We should make a computer for people who want to do something other than configure computers. Therefor, the Mac engineers had to make the computer smart. You have a smart monitor talking to a dumb computer. I do not mean to be insulting, it is just a label like master and slave. (Bill is the master and customers are his slaves! : ) OK, maybe my brand loyalty is showing.) Just consider the Windows error message "Cannot find driver for the new hardware." The new hardware is the monitor that is displaying the error message that says it cannot see the monitor that is displaying the error message that .... Go figure.

Seriously, the monitor you are trying to configure is one of Apple's earliest multi-sync products. As Grant mentioned, Apple sometimes takes a different approach.

"I tried to change the monitor type from Nec MultiSync XV17+"

NEC, on the otherhand, had it right from the start. At government auctions, everyone would bid twice as much for an NEC than other brands because the monitors set the standard for compatibility. Newer computers look at the monitor to see what resolution to use and a multi-sync monitor is capable of responding to multiple signals. Either the computer or the monitor has to decide on a frequency or they go nowhere in their little signal dance. Add energy save features and you really have conflicts.

Bottom line? You will have to overcome the signal differences between the two standards. Or, find a government auction or a Goodwill store or someone that is giving away a VGA monitor. WSU sells them for $1. Goodwill throws them away. Landfills do not want them. It will be faster to find a free VGA/SVGA monitor than to configure the Apple product.

On the otherhand, if you want to take a trip down memory lane and learn all the painful configuration issues from E Machines (1988 company, not the current company), Raster Opts, SuperMac/SuperMatch and other discontinued companies, we would be happy to take you through the tortured steps to get monitors to talk properly.

Some hackers want to get a 68000 machine on the internet as an academic exercise. That is great. If you want me to take apart an Apple 15" Multi-Scan
and test all the leads, I would be happy to do that as well. Most just want a monitor to work. In that case, find an NEC and enjoy.

Let us know your pleasure.

Ji˜m

Jim-

Thanks for weighing in.
I don't share your cynicism. Examining the interface would be helpful in most cases, but will not help this dilemma.

I think the specs for an NEC 17" should work fine for now. Set it for 640 by 480 with the NEC attached, then pull the Video cable "live" and substitute the Apple monitor. You should get a picture. Then proceed with caution setting a higher resolution, being careful to set only the resolutions the Apple display can handle.

Calling these personality files for specific monitors "drivers" is a real misnomer. The Electrical Interface is so fast there is no way it can be controlled with software.

The interface is predetermined, and always the same: Red, Green, and Blue data and H-Sync and V-Sync. One line of data is displayed between regular pulses on H-Sync, and the screen is restarted from the top with regular pulses in V-Sync. The whole screen is redrawn EVERY 60 to 100 times per second.

The only variables are: how fast is one row of data provided for each row (Horizontal refresh rate) and How fast is one complete set of lines (one complete screen) provided (Vertical Refresh rate). But those speeds mean the difference between stable picture on one hand, and rolling screen, tearing, squirming picture or no picture.

Grant,

"the specs for an NEC 17" should work fine for now. Set it for 640 by 480 with the NEC attached, then pull the Video cable "live" and substitute the Apple monitor."

The key word is "live." Once the computer sees something connected it should 'auto configure' and display something. I agree that switching live is the best advice. I assumed that the only reason for using the Apple monitor was that the NEC was dead or gone or just the last 'profile on record.' As such, it would not be available for that first step in the dance of communication.

Quoting you from another discussion:

"In my opinion, some users are looking for a narrow answer, like "what does it look like" and others want all the background then can get. Tom "Texas Mac Man" has a large PRAM battery tutorial with multiple references on his site, but there is so much information there that some may find it baffling and are not willing to wade through it all. I think there is room for both the "long answer" and the "short answer".
Like many things on the web, a site may provide a banquet of information, on your subject or a related subject, but if you are careful you can still use it to "snack" on just the information you crave. "

Craig, how much do you want plug and play vs. getting it to work at all costs to save money? How much tinkering vs. get 'r done?

I am reminded of the gal from australia who responded to a long response to a post "what a mouthful!" She slowly digested it all and got her computer working but she had hoped for a quick and easy fix. It wasn't quick and it wasn't easy. : )

We can get it to work, just how much work is up to you.

Ji˜m

On the beige G3's built-in Video, 2 MB of VRAM will run the display at up to 1152 by 870 at 16-bit (= PC HI Color mode); if you are willing to settle for 256-color, it goes all the way up to 1920 by 1080.

The spec I cited above list the display's refresh rates. I can paste them here, but it will not be a pretty table:

Mode - Resolution - VertRate - Horiz Rate - DPI
VGA . . . . . - 640x480 - 60 Hz - 31.77 kHz - 58
Macintosh - 640x480 - 66.7 Hz - 35.0 kHz - 58
SVGA . . . . - 800x600 - 60 Hz - 37.9 kHz - 73
SVGA . . . . - 800x600 - 72 Hz - 48.1 kHz - 73
Macintosh - 832x624 - 75 Hz - 49.7 kHz - 76
VESA . . . . - 1024x768 - 60 Hz - 48.4 kHz - 93
1024 x768 - 1024x768 - 70 Hz - 56.5 kHz - 93
Macintosh - 1024x768 - 75 Hz - 60.5 kHz - 93