Quadra Video Notes

From: mem@jhufos.pha.jhu.edu (Mel Martinez x8378) Subject: [*]Quadra video overview (tech) Date: Tue, 14 Jul 92 15:20:11 EDT Due to the number of private requests I keep getting for info on the quadra videos, I can't get any of my own work done! :) I am forwarding the following document to the archives. It describes the quadra internal video very well and should be very useful to many quadra owners. It is written by the designer of the quadra video himself, Dale Adams, and was originally posted in comp.sys.mac.hardware (I think). Please archive as info-mac/tech/quadra-video-notes.txt Mel Martinez The Johns Hopkins University Dept. of Physics -- snip here -- > From: Dale_Adams@gateway.qm.apple.com (Dale Adams) > Newsgroups: comp.sys.mac.hardware > Subject: Mac Quadra Video Explained, Part 1 > Date: 25 Nov 91 16:39:34 GMT > Organization: Apple Computer, Inc., Cupertino, CA Macintosh Quadra Built-In Video, Part 1: Video Architecture There have been quite a few questions in this (and other) news groups concerning the built-in video capabilities of the new Macintosh Quadra 700 and 900. In response to these questions, here is the first of three articles which provide an in-depth (and accurate!) description of the Quadra video capabilities. This first article discusses a number of general Quadra video topics, the second details how to wire the video connector sense pins to access all the Quadra's supported video modes, and the third describes the memory configurations necessary to support each of the video modes at specific pixel depths. And by the way, I am the designer of the video hardware for both Mac Quadras, so this information is accurate. The Quadras were designed with a flexible video hardware section in order to support a wide variety of displays. Since the purchaser of one of these CPUs is paying for a frame buffer on the motherboard (whether (s)he wants it or not), and since the Quadras were designed to be high performance machines, the frame buffer was designed to be both very flexible (to support most displays a user may want to use) and to be relatively high performance (to match the computer's capabilities). Obviously every display made by every 3rd party monitor vendor can't be supported by the onboard video, but the Quadras do support a much wider range of displays at a higher level of performance than any previous Macintosh. The Quadra 700 and 900 support pixel depths ranging from 1 to 32 bits per pixel (bpp), Apple displays ranging from the 512 x 384 12-inch color monitor through the 1152 x 870 21-inch color monitor, pixel clocks ranging from 12 to 100 MHz, and a variety of industry standards such as VGA, SVGA, NTSC, and PAL. The Mac Quadra video port produces RS-343 RGB, and also provides horizontal, vertical and composite sync outputs. Composite or S-video output is not provided, but can be accomplished by use of an external RGB-to-composite encoder. The Quadra 700 and 900 also …